Recombinant Rat Long-chain fatty acid transport protein 1 (Slc27a1)

What is the molecular structure of Recombinant Rat SLC27A1?

Recombinant Rat SLC27A1 (FATP1) is a membrane and cytoplasmic protein with a predicted molecular mass of 35.4 kDa and an experimentally verified mass of 35 kDa. The commercially available recombinant protein typically contains residues Glu191~Lys475 with an N-terminal His Tag to facilitate purification and detection . The protein has an isoelectric point of 8.0, which is important to consider when designing buffer systems for experimental applications . The protein's structure includes membrane-spanning domains that facilitate its role in fatty acid transport across the plasma membrane, with specific domains responsible for both transport and acyl-CoA synthetase activity .

What are the primary functions of SLC27A1 in cellular metabolism?

SLC27A1 plays critical roles in cellular metabolism by mediating the translocation of long-chain fatty acids (LCFA) across the plasma membrane. This transport function is essential for numerous physiological processes including:

• Membrane phospholipid synthesis

• Intracellular signal transduction

• Energy metabolism and ATP production

• Posttranslational modifications of proteins

• Transcriptional regulation of metabolic genes

Importantly, SLC27A1 function is hormone-regulated in a tissue-specific manner. In adipocytes, insulin stimulation induces a rapid translocation of SLC27A1 from intracellular compartments to the plasma membrane, resulting in increased LCFA uptake. This insulin responsiveness is not observed in myocytes, highlighting the tissue-specific regulation of this transport protein .

How does SLC27A1 differ from other fatty acid transport proteins?

SLC27A1 is one of six members (SLC27A1-6) in the solute carrier family 27. While all members facilitate fatty acid transport, they differ in:

• Tissue distribution: SLC27A1 is predominantly expressed in adipose tissue, heart, and skeletal muscle

• Substrate specificity: Different affinities for fatty acid chain lengths

• Regulatory mechanisms: As noted above, SLC27A1 shows insulin-responsive translocation in adipocytes but not myocytes

• Enzymatic activity: SLC27A1 has intrinsic acyl-CoA synthetase activity, allowing it to not only transport fatty acids but also participate in their activation

These differences contribute to the specialized roles of each SLC27 family member in fatty acid metabolism and explain why dysfunction of specific transporters is associated with distinct metabolic phenotypes .

What are the optimal conditions for reconstitution and storage of Recombinant Rat SLC27A1?

For optimal reconstitution and storage of Recombinant Rat SLC27A1:

• Reconstitution protocol:

  • Reconstitute in 10mM PBS (pH 7.4) to a concentration of 0.1-1.0 mg/mL

  • Critical: Do not vortex the solution as this may damage the protein structure

  • Allow the freeze-dried powder to dissolve completely at room temperature with gentle agitation

• Storage recommendations:

  • Short-term (up to one month): Store at 2-8°C

  • Long-term: Aliquot and store at -80°C for up to 12 months

  • Avoid repeated freeze/thaw cycles as this significantly reduces protein activity

• Stability considerations:

  • The thermal stability can be assessed through accelerated degradation testing (48h at 37°C)

  • Under appropriate storage conditions, the loss rate should be less than 5% within the expiration date

These conditions are crucial for maintaining protein integrity and biological activity for experimental applications.

What PCR conditions and primers are recommended for rat SLC27A1 gene expression analysis?

For reliable gene expression analysis of rat SLC27A1, researchers should follow these PCR conditions and use validated primers:

Primer sequences (based on accession number NM_001039602.1):

• Forward primer: 5'-TGCCTTCCGCTCTACCAC-3'

• Reverse primer: 5'-TCAACCCGTTTGCCCACT-3'

PCR conditions:

• Annealing temperature: 59°C (optimal for these specific primers)

• Expected product size: 239 bp

• Reaction components: Standard qPCR master mix with SYBR Green or probe-based detection

• Cycling conditions: Initial denaturation (95°C, 3 min), followed by 40 cycles of denaturation (95°C, 15 sec), annealing (59°C, 30 sec), and extension (72°C, 30 sec)

For quantitative analysis, reference genes such as GAPDH or β-actin should be included, and the comparative Ct (2^-ΔΔCt) method can be used to calculate relative expression levels. This approach has been validated in published studies examining SLC27A1 expression patterns in relation to fatty acid metabolism .

How can I detect and quantify SLC27A1 protein in tissue or cell samples?

Multiple complementary approaches can be used to detect and quantify SLC27A1 protein:

• Western Blotting:

  • Sample preparation: Tissue homogenization or cell lysis in buffer containing protease inhibitors

  • Protein separation: SDS-PAGE (10-12% gel recommended for 35 kDa proteins)

  • Transfer: PVDF or nitrocellulose membrane (0.45 μm pore size)

  • Blocking: 5% non-fat milk or BSA in TBST

  • Primary antibody: Anti-SLC27A1 (1:1000 dilution, overnight at 4°C)

  • Detection: HRP-conjugated secondary antibody with chemiluminescence

• ELISA-based quantification:

  • Commercial sandwich ELISA kits are available with detection ranges of 0.312-20 ng/mL

  • Sensitivity: Typically around 0.166 ng/mL

  • Sample types: Serum, plasma, tissue lysates, and cell culture supernatants

  • Intra-assay CV: 7.8%; Inter-assay CV: 9.1%

• Immunohistochemistry/Immunofluorescence:

  • Fixation: 4% paraformaldehyde

  • Permeabilization: 0.1% Triton X-100 (for accessing intracellular SLC27A1)

  • Primary antibody incubation: Anti-SLC27A1 (1:200, overnight at 4°C)

  • Visualization: Fluorophore-conjugated secondary antibody or HRP-DAB system

For subcellular localization studies, co-staining with membrane markers (e.g., Na+/K+-ATPase) and cytoplasmic markers is recommended to distinguish between membrane-bound and intracellular pools of SLC27A1 .

How does insulin regulate SLC27A1 trafficking and activity in different tissues?

The regulation of SLC27A1 trafficking and activity by insulin demonstrates tissue-specific mechanisms with important metabolic implications:

Adipocyte regulation:

• In the basal state, SLC27A1 is predominantly localized in intracellular compartments

• Insulin stimulation triggers rapid translocation of SLC27A1 to the plasma membrane

• This translocation is dependent on PI3K signaling pathway activation

• The increased membrane localization directly correlates with enhanced LCFA uptake capacity

• This mechanism likely contributes to increased triglyceride storage in adipose tissue during postprandial states

Myocyte regulation:

To study these tissue-specific differences experimentally:

• Use subcellular fractionation to separate membrane and cytosolic pools

• Employ pulse-chase experiments with labeled fatty acids to track transport kinetics

• Compare acute vs. chronic insulin exposure effects

• Apply inhibitors of various trafficking pathways (e.g., cytoskeletal disrupting agents, PI3K inhibitors)

Understanding these regulatory mechanisms is critical for developing targeted approaches to metabolic disorders characterized by dysregulated fatty acid handling .

What experimental models are available to study SLC27A1 function in vivo?

Several experimental models have been developed to study SLC27A1 function in vivo:

Knockout mouse models:

• Global SLC27A1-knockout mice display:

  • Reduced fatty acid uptake in adipose and heart tissues

  • Protection against high-fat diet-induced insulin resistance

  • Altered adipocyte size and distribution

  • Changes in whole-body energy expenditure

Tissue-specific transgenic models:

• Muscle-specific SLC27A1 overexpression models:

  • Increased intramyocellular lipid accumulation

  • Development of insulin resistance despite normal body weight

  • Altered mitochondrial function and oxidative capacity

Inducible expression systems:

• Tetracycline-responsive SLC27A1 expression:

  • Allows temporal control of SLC27A1 expression

  • Useful for distinguishing developmental vs. acute metabolic effects

  • Permits study of tissue adaptation to altered fatty acid uptake

In vivo imaging approaches:

• Radiolabeled fatty acid tracers with PET imaging:

  • Non-invasive assessment of tissue-specific fatty acid uptake

  • Can be combined with genetic models to determine SLC27A1 contribution

  • Allows longitudinal studies of metabolic adaptation

Disease models with SLC27A1 relevance:

• Diet-induced obesity models

• Streptozotocin-induced diabetes

• Exercise training models to study adaptive responses

When designing experiments using these models, researchers should consider:

• Background strain effects on metabolic phenotypes

• Compensatory upregulation of other fatty acid transporters

• Sex-specific differences in fatty acid metabolism

• Age-dependent changes in SLC27A1 expression and function

How does SLC27A1 interact with PPAR signaling pathways?

SLC27A1 and PPAR signaling pathways exhibit bidirectional regulatory interactions with significant implications for metabolic regulation:

SLC27A1 effects on PPAR signaling:

• SLC27A1-mediated fatty acid uptake increases intracellular availability of fatty acids that serve as PPAR ligands

• The acyl-CoA synthetase activity of SLC27A1 generates fatty acyl-CoAs that can be further metabolized to PPAR-activating lipid species

• Studies have shown SLC27A1 expression levels directly correlate with PPAR transcriptional activity

PPAR regulation of SLC27A1:

• The SLC27A1 gene promoter contains PPAR response elements (PPREs)

• PPAR agonists (particularly PPARγ agonists) upregulate SLC27A1 expression

• This creates a feed-forward loop: increased PPAR activity → increased SLC27A1 → increased fatty acid uptake → further PPAR activation

Experimental evidence:

• Gene expression analyses have shown SLC27A1 is significantly enriched in PPAR signaling pathways

• In animal studies, SLC27A1 expression correlates with measures of PPAR activity

• Hexanal content studies have demonstrated that SLC27A1 and other genes within the PPAR signaling pathway (ACOX3, NR4A1, VEGFA, JUN, EGR1) show coordinated expression patterns

Experimental approaches to study this interaction:

• Chromatin immunoprecipitation (ChIP) assays to confirm PPAR binding to SLC27A1 promoter

• Luciferase reporter assays with SLC27A1 promoter constructs

• Combined treatment with PPAR agonists and SLC27A1 inhibitors

• Metabolomic profiling to identify specific lipid species involved in the feedback loop

Understanding this interaction is particularly relevant for metabolic diseases where both fatty acid transport and PPAR signaling are dysregulated .

How can I optimize SLC27A1 activity assays for experimental applications?

Optimizing SLC27A1 activity assays requires careful consideration of both transport function and acyl-CoA synthetase activity:

Fatty acid uptake assays:

• Fluorescent fatty acid analogs:

  • BODIPY-labeled fatty acids (BODIPY-FA)

  • Optimize concentration (typically 0.5-2 μM)

  • Include time-course analysis (0-30 minutes)

  • Compare uptake with and without metabolic inhibitors to distinguish transport from metabolism

• Radiolabeled assays:

  • [³H] or [¹⁴C]-labeled long-chain fatty acids

  • Pulse-chase design (30 second to 5 minute pulses)

  • Rapid termination of uptake with ice-cold, albumin-containing buffer

  • Separation of membrane-bound vs. internalized fatty acids using acid wash steps

Acyl-CoA synthetase activity:

• Enzymatic coupled assays:

  • Measure AMP production by coupling to additional enzymatic reactions

  • Monitor spectrophotometrically at 340 nm

  • Optimize buffer conditions (pH 7.4-8.0, 1-5 mM ATP, 0.2-1 mM CoA)

  • Include controls with heat-inactivated protein

• Direct measurement of acyl-CoA formation:

  • HPLC analysis of acyl-CoA products

  • LC-MS/MS for detailed profiling of specific acyl-CoA species

  • Use internal standards for quantification

Critical considerations:

• Buffer composition:

  • Use physiological pH (7.4)

  • Include ATP (1-5 mM) and CoA (0.1-1 mM) for activation assays

  • Add MgCl₂ (5 mM) as a cofactor

  • Consider adding appropriate detergents (0.01-0.05% mild non-ionic detergents) for membrane protein stability

• Substrate preparation:

  • Pre-complex long-chain fatty acids with BSA (3:1 molar ratio FA:BSA)

  • Ensure complete solubilization without precipitation

  • Use fresh substrate preparations to avoid oxidation

• Temperature control:

  • Conduct assays at physiological temperature (37°C)

  • Maintain consistent temperature throughout experiments

• Positive and negative controls:

  • Include known SLC27A1 inhibitors as negative controls

  • Use tissue extracts with high endogenous SLC27A1 activity as positive controls

What are the common challenges in expressing and purifying functional recombinant SLC27A1?

Expressing and purifying functional recombinant SLC27A1 presents several challenges due to its membrane protein nature:

Expression system selection:

• Prokaryotic systems (E. coli):

  • Advantages: High yield, cost-effective, established protocols

  • Challenges: Proper folding, lack of post-translational modifications, inclusion body formation

  • Solution: Use specialized strains (C41/C43), lower induction temperature (16-20°C), fusion tags (SUMO, MBP)

• Eukaryotic systems:

  • Insect cells (Sf9/Sf21): Better folding of membrane proteins

  • Mammalian cells: Proper post-translational modifications but lower yield

  • Yeast systems: Compromise between yield and proper folding

Solubilization and purification challenges:

• Detergent selection:

  • Critical for maintaining protein structure and activity

  • Test panel of detergents (DDM, LMNG, digitonin)

  • Consider bicelle or nanodisc systems for improved stability

• Purification strategy:

  • Two-step purification recommended: Affinity chromatography followed by size exclusion

  • His-tag positioning affects purification efficiency (N-terminal typically preferred)

  • Include stabilizing agents (glycerol 10%, cholesterol hemisuccinate)

• Activity preservation:

  • Monitor activity throughout purification process

  • Include lipids during purification to maintain native-like environment

  • Consider co-purification with lipids or reconstitution into liposomes

Quality control measures:

• Western blotting to confirm identity and integrity

• Size exclusion chromatography to assess monodispersity

• Functional assays to verify activity preservation

• Thermal stability assays to optimize buffer conditions

Yield optimization strategies:

• Screen multiple constructs with varying boundaries

• Codon optimization for expression system

• Optimize induction parameters (IPTG concentration, temperature, duration)

• Consider fusion partners that enhance solubility and expression

How can I address inconsistent results in SLC27A1 functional studies?

Inconsistent results in SLC27A1 functional studies often stem from several key factors that can be systematically addressed:

Sample preparation variability:

• Tissue/cell homogenization:

  • Standardize homogenization method (Dounce vs. sonication)

  • Maintain consistent buffer-to-sample ratios

  • Process all samples identically (time, temperature)

  • Include protease/phosphatase inhibitors freshly prepared

• Protein stability considerations:

  • Avoid repeated freeze-thaw cycles

  • Perform activity assays with freshly prepared samples when possible

  • Aliquot proteins to minimize degradation

Experimental condition variability:

• Fatty acid preparation:

  • Use consistent FA:BSA ratios (3:1 recommended)

  • Prepare fresh substrates for each experiment

  • Verify substrate solubility before use

  • Store protected from light to prevent oxidation

• Buffer composition effects:

  • pH sensitivity: SLC27A1 activity optimal at pH 7.4-7.6

  • Ion requirements: Ensure consistent Mg²⁺ concentration

  • ATP quality: Use fresh ATP solutions

  • Detergent critical micelle concentration: Maintain above CMC but below inhibitory levels

Analytical considerations:

• Detection method sensitivity:

  • Establish signal linearity range for each assay

  • Include internal standards for normalization

  • Run technical replicates (minimum triplicate)

  • Calculate and report coefficient of variation

• Data analysis approaches:

  • Apply appropriate controls for background subtraction

  • Consider kinetic parameters rather than single timepoint measurements

  • Use biological replicates to account for inherent variability

  • Apply appropriate statistical tests for data interpretation

Biological variability considerations:

• Tissue-specific SLC27A1 regulation:

  • Account for nutritional/hormonal status of source material

  • Consider circadian regulation of expression

  • Document age and sex differences

  • Control for potential compensatory expression of other fatty acid transporters

• Experimental design recommendations:

  • Include positive controls (tissues with known high SLC27A1 activity)

  • Use pharmacological inhibitors as negative controls

  • Consider siRNA/shRNA knockdown validation studies

  • Document and control environmental variables (temperature, CO₂, humidity)

How is SLC27A1 involved in metabolic disease pathophysiology?

SLC27A1 plays crucial roles in metabolic disease pathophysiology through several interconnected mechanisms:

Insulin resistance and Type 2 diabetes:

• Aberrant SLC27A1 activity contributes to ectopic lipid accumulation in muscle and liver

• Lipid oversupply leads to ceramide and diacylglycerol accumulation, activating PKC isoforms

• This activation impairs insulin signaling through serine phosphorylation of IRS proteins

• Reduced insulin sensitivity creates a vicious cycle of further dysregulated lipid metabolism

• SLC27A1 knockout models show protection against diet-induced insulin resistance, supporting its causative role

Obesity pathophysiology:

• In adipose tissue, SLC27A1 mediates fatty acid uptake for triglyceride synthesis

• During obesity, adipose SLC27A1 expression patterns change, contributing to altered fat distribution

• Visceral vs. subcutaneous adipose depots show differential SLC27A1 regulation

• These differences may explain depot-specific contributions to metabolic risk

Cardiovascular implications:

• In cardiomyocytes, SLC27A1 facilitates fatty acid uptake for energy production

• During pathological conditions, excessive cardiac lipid accumulation leads to lipotoxicity

• This contributes to cardiomyopathy development in metabolic disease

• SLC27A1 modulation may offer cardioprotective effects in metabolic syndrome

Experimental approaches to study SLC27A1 in disease:

• Tissue-specific gene expression analysis in human metabolic disease cohorts

• Correlation of SLC27A1 SNPs with disease risk and progression

• Metabolic phenotyping of genetic models with altered SLC27A1 expression

• Pharmacological targeting to assess therapeutic potential

This multifaceted involvement makes SLC27A1 a potential therapeutic target for metabolic disease intervention, particularly for conditions characterized by ectopic lipid accumulation and insulin resistance .

What are emerging techniques for studying SLC27A1 localization and dynamics?

Cutting-edge techniques for studying SLC27A1 localization and dynamics provide unprecedented insights into its cellular functions:

Advanced imaging approaches:

• Super-resolution microscopy:

  • STORM/PALM techniques achieve 10-20 nm resolution

  • Direct visualization of SLC27A1 clustering and membrane organization

  • Advantages: Detailed analysis of protein organization beyond diffraction limit

  • Applications: Tracking insulin-stimulated SLC27A1 translocation patterns

• Live-cell imaging with fluorescent protein fusions:

  • GFP/mCherry-tagged SLC27A1 for real-time trafficking studies

  • Photoactivatable/photoswitchable fluorophores for pulse-chase experiments

  • FRAP (Fluorescence Recovery After Photobleaching) to assess membrane mobility

  • Applications: Quantifying kinetics of insulin-stimulated translocation

• FRET/BRET approaches:

  • Measure protein-protein interactions in live cells

  • Study SLC27A1 interactions with other membrane proteins or cytoskeletal elements

  • Applications: Identifying novel regulators of SLC27A1 localization

Molecular and biochemical techniques:

• Proximity labeling methods:

  • BioID or APEX2 fusion proteins to identify proximal interacting partners

  • TurboID for rapid labeling of neighboring proteins

  • Applications: Mapping the dynamic SLC27A1 interactome under various conditions

• Advanced membrane fractionation:

  • Lipid raft isolation to assess SLC27A1 distribution in membrane microdomains

  • Differential centrifugation with marker validation for precise subcellular localization

  • Applications: Determining how membrane composition affects SLC27A1 function

• CRISPR-Cas9 genome editing:

  • Endogenous tagging of SLC27A1 to avoid overexpression artifacts

  • Knock-in of specific mutations to study trafficking motifs

  • Applications: Creating cellular models with physiologically relevant expression levels

Emerging analytical approaches:

• Single-molecule tracking:

  • Quantum dot labeling of SLC27A1 for long-term tracking

  • Analysis of diffusion coefficients and confinement zones

  • Applications: Understanding the relationship between mobility and transport activity

• Artificial intelligence-assisted image analysis:

  • Machine learning algorithms for automated detection of translocation events

  • Quantitative analysis of complex localization patterns

  • Applications: High-throughput screening of compounds affecting SLC27A1 trafficking

These advanced techniques provide powerful tools for understanding the dynamic regulation of SLC27A1 localization and how it relates to metabolic disease pathophysiology .

How do post-translational modifications regulate SLC27A1 function?

Post-translational modifications (PTMs) are critical regulators of SLC27A1 function, affecting its activity, localization, and interactions with other proteins:

Phosphorylation:

• Insulin-stimulated phosphorylation:

  • Insulin receptor activation leads to PI3K-dependent phosphorylation of SLC27A1

  • Specific serine/threonine residues are targeted

  • These modifications trigger translocation from intracellular compartments to plasma membrane

  • Mutation of key phosphorylation sites impairs insulin-stimulated fatty acid uptake

• AMPK-mediated phosphorylation:

  • Energy stress activates AMPK, which can phosphorylate SLC27A1

  • This modification appears to affect both localization and intrinsic activity

  • Creates a regulatory mechanism linking energy status to fatty acid uptake

Ubiquitination:

• Regulation of protein turnover:

  • K48-linked ubiquitination targets SLC27A1 for proteasomal degradation

  • Chronic insulin exposure can increase ubiquitination and decrease protein levels

  • This provides a mechanism for long-term adaptation to metabolic conditions

• Non-degradative ubiquitination:

  • K63-linked ubiquitination may regulate trafficking without promoting degradation

  • Could serve as a sorting signal for endosomal transport

Glycosylation:

• N-linked glycosylation at specific asparagine residues

• Affects protein folding, stability, and cell surface expression

• May create recognition sites for lectin-mediated sorting pathways

Palmitoylation:

• Affects membrane microdomain localization

• Regulates association with lipid rafts

• Dynamic modification that can be enzymatically regulated

Experimental approaches to study PTMs:

• Mass spectrometry-based proteomics:

  • Identification of specific modified residues

  • Quantitative analysis of modification stoichiometry under different conditions

  • Enrichment strategies for phosphopeptides or ubiquitinated peptides

• Site-directed mutagenesis:

  • Generation of non-modifiable mutants (S→A, K→R)

  • Phosphomimetic mutations (S→D/E)

  • Functional analysis of mutants in cellular models

• PTM-specific antibodies:

  • Western blotting with phospho-specific antibodies

  • Immunoprecipitation to enrich modified forms

Understanding these PTMs provides insight into the dynamic regulation of SLC27A1 and potential therapeutic targets for modulating its function in metabolic disease .

What are the most promising future directions in SLC27A1 research?

Future SLC27A1 research holds significant promise in several key areas that could transform our understanding of fatty acid metabolism and metabolic disease:

Therapeutic targeting approaches:

• Development of selective SLC27A1 inhibitors to prevent ectopic lipid accumulation

• Tissue-specific modulation strategies to address metabolic syndrome

• Combination approaches targeting multiple fatty acid transporters simultaneously

• Assessment of existing drugs (e.g., thiazolidinediones) for effects on SLC27A1 regulation

• Novel drug delivery systems for targeting SLC27A1 in specific tissues

Advanced structural biology:

• Cryo-EM structures of full-length SLC27A1 in different conformational states

• Molecular dynamics simulations to understand transport mechanisms

• Structure-based drug design targeting specific functional domains

• Identification of allosteric regulatory sites for pharmacological intervention

Systems biology integration:

• Multi-omics approaches linking genotype to metabolic phenotypes

• Network analysis of SLC27A1 interactions with metabolic pathways

• Mathematical modeling of fatty acid transport kinetics across tissues

• Integration with whole-body metabolic regulation models

Clinical translation:

• Biomarker development based on SLC27A1 function or expression

• Personalized medicine approaches targeting specific SLC27A1 variants

• Non-invasive imaging of fatty acid transport in human disease

• Clinical trials of therapies targeting SLC27A1-mediated pathways

Emerging research questions:

• How does SLC27A1 contribute to adipose tissue browning and energy expenditure?

• What role does SLC27A1 play in cancer metabolism and lipid reprogramming?

• How do circadian rhythms impact SLC27A1 regulation and function?

• What is the interplay between SLC27A1 and mitochondrial fatty acid oxidation?

• How does SLC27A1 participate in inflammatory signaling in metabolic disease?