AIG1 Antibody

What is AIG1 protein and what is its biological function?

AIG1 (Androgen-Induced 1) is a 28 kDa multipass transmembrane protein with 5-6 predicted transmembrane domains. It functions as a hydrolase that specifically targets bioactive fatty-acid esters of hydroxy-fatty acids (FAHFAs), but not other major classes of lipids. AIG1 shows a preference for FAHFAs with branching distal from the carboxylate head group of the lipids. The protein was originally discovered as an androgen-induced gene product from human dermal papilla cells .

What are the alternative names for AIG1 protein?

AIG1 is also known by several other designations in scientific literature and databases, including CGI-103, AIG-1, Fatty acid esters of hydroxy fatty acids hydrolase AIG1, and FAHFA hydrolase AIG1. Understanding these alternative nomenclatures is important when conducting comprehensive literature reviews on this protein .

What epitope regions of AIG1 are typically targeted by commercial antibodies?

Commercial AIG1 antibodies target various regions of the protein. Common epitopes include the N-terminal region (such as amino acids 53-81), C-terminal region, and specific amino acid sequences including AA 51-100, AA 50-100, and AA 187-236. When selecting an antibody, researchers should consider which protein domain is most relevant to their research question, as well as accessibility of the epitope in experimental conditions .

How do I select the appropriate AIG1 antibody for my specific application?

Selection should be based on several factors including the planned application (WB, IF, IHC, ELISA), species of study (human, mouse, rat), specific epitope requirements, and validation data available. For instance, if studying potential protein interactions at the N-terminus, an N-terminal specific antibody would be more appropriate. Review the validation data showing reactivity with your species of interest and application method before selection .

What is the difference between the various AIG1 antibody preparations available?

AIG1 antibodies differ in several aspects:

• Epitope recognition (N-term, C-term, specific amino acid regions)

• Host species (predominantly rabbit)

• Clonality (most are polyclonal)

• Purification method (affinity chromatography, protein A)

• Conjugation status (unconjugated, APC-conjugated, biotin-conjugated)

• Validated applications (WB, IF, IHC, ELISA)

• Species reactivity profiles (human, mouse, rat)

What are the recommended protocols for Western blot analysis using AIG1 antibodies?

For Western blot applications with AIG1 antibodies, follow these methodological guidelines:

• Use 15-20 μg of total protein from tissue lysates or cell lines

• Apply dilutions ranging from 1:500-1:3000 depending on the specific antibody

• Expect bands at approximately 28-32 kDa

• For recombinant tagged variants, additional bands at 25 and 15 kDa may be observed

• Validated positive controls include K-562 cells, PC-3 cells, mouse/rat heart tissue, mouse/rat ovary tissue, and mouse testis tissue

What are the optimal conditions for immunohistochemistry with AIG1 antibodies?

For IHC applications, the following methodology is recommended:

• Use paraffin-embedded tissue sections

• Apply antibody dilutions between 1:20-1:200

• For antigen retrieval, use TE buffer pH 9.0 (alternatively, citrate buffer pH 6.0)

• Human ovary tumor tissue has been validated as a positive control

• For visualization, both colorimetric and fluorescence-based detection methods are compatible

What tissue and cell types show reliable AIG1 expression for use as positive controls?

Based on validated experimental data, the following samples serve as reliable positive controls for AIG1 detection:

This table is derived from experimental validation data across multiple antibodies and can guide sample selection for controls .

How can AIG1 protein interactions be studied using antibody-based approaches?

For studying AIG1 protein interactions, consider these methodological approaches:

• Immunoprecipitation followed by mass spectrometry

• Proximity ligation assays for in situ protein interaction visualization

• Co-immunoprecipitation with potential interaction partners

• FRET/BRET assays using tagged AIG1 variants

When using AIG1 antibodies for protein interaction studies, it's critical to verify that the epitope recognized doesn't interfere with binding regions. The data showing AIG1's reactivity with FP-probes suggests potential active sites that should be considered when designing interaction studies .

What experimental approaches can resolve the discrepancy between predicted and observed molecular weights of AIG1?

To address the molecular weight discrepancies observed with AIG1 (predicted 28 kDa versus observed bands of 25 and 15 kDa in some experiments), consider these methodological approaches:

• Deglycosylation assays to identify post-translational modifications

• Mass spectrometry analysis of purified protein

• Site-directed mutagenesis of potential cleavage sites

• N-terminal sequencing of the smaller fragments

• Expression of truncated constructs to map fragment identity

Research has shown that variants of AIG1 expressed without C-terminal epitope tags migrate as ~15-17 kDa proteins, suggesting potential processing or alternative start sites that warrant further investigation .

How can AIG1's enzymatic activity as a FAHFA hydrolase be measured in experimental settings?

To assess AIG1's hydrolase activity against fatty acid esters of hydroxy fatty acids (FAHFAs), researchers can employ these methodological approaches:

• In vitro assays using purified recombinant AIG1 and synthetic FAHFA substrates

• LC-MS/MS detection of FAHFA hydrolysis products

• Activity-based protein profiling with fluorophosphonate probes (FP-Rh, FP-alkyne)

• Competitive inhibition assays to determine substrate specificity

• Site-directed mutagenesis of conserved Thr and His residues to confirm catalytic mechanism

The research findings indicate AIG1 shows time-dependent, irreversible labeling with FP-Rh, which is competitively blocked by FP-alkyne, providing a useful methodological approach for activity studies .

What are common issues in Western blot detection of AIG1 and how can they be resolved?

When troubleshooting Western blots for AIG1 detection, consider these methodological solutions:

These recommendations are based on observed experimental challenges with AIG1 detection in various tissue and cell types .

How can specificity of AIG1 antibodies be validated in experimental settings?

To validate AIG1 antibody specificity, implement these methodological controls:

• Peptide competition assays using the immunizing peptide (e.g., synthetic peptide from AA 53-81 for N-terminal antibodies)

• siRNA or CRISPR knockout of AIG1 in cell lines followed by Western blot

• Parallel testing with multiple antibodies targeting different epitopes

• Testing in known positive (heart, ovary) and negative control tissues

• Recombinant expression of tagged AIG1 as a positive control

These validation steps are particularly important given AIG1's status as a transmembrane protein with multiple predicted domains and processing variants .

What are the experimental considerations when using AIG1 antibodies across different species?

When using AIG1 antibodies across human, mouse, and rat samples, consider these methodological guidelines:

• Verify sequence homology at the epitope region between species

• Validate using species-specific positive controls (e.g., mouse heart tissue for mouse studies)

• Adjust antibody concentrations for cross-species applications

• For rodent studies, antibodies targeting AA 53-81 or AA 50-100 regions show reliable cross-reactivity

• Species-specific secondary antibodies should be used to minimize background

The experimental evidence indicates human, rat, and mouse variants of AIG1 all react with FP-Rh probes, suggesting conservation of functional domains across these species .

What is the relationship between AIG1's androgen-responsiveness and its enzymatic function?

While AIG1 was originally identified as an androgen-induced gene in dermal papilla cells, its enzymatic function as a FAHFA hydrolase raises interesting questions about the connection between androgen signaling and lipid metabolism. To investigate this relationship:

• Perform chromatin immunoprecipitation to validate androgen receptor binding to AIG1 promoter

• Measure AIG1 expression and FAHFA hydrolase activity in response to androgen treatment

• Analyze tissue-specific expression patterns in relation to androgen-responsive tissues

• Investigate potential metabolic phenotypes in AIG1 knockout models

• Study correlation between androgen levels and FAHFA profiles in clinical samples

This represents an important area for further research that connects hormone signaling to specific enzymatic functions in lipid metabolism .

How do conserved Thr and His residues contribute to AIG1's catalytic mechanism?

The search results mention conserved Thr and His residues in AIG1, suggesting a potential catalytic mechanism. To elucidate their role:

• Perform site-directed mutagenesis of these conserved residues

• Assess enzyme kinetics with wild-type versus mutant proteins

• Use homology modeling to predict the three-dimensional arrangement of the active site

• Apply molecular dynamics simulations to understand conformational changes during catalysis

• Compare with other hydrolase families containing Thr/His catalytic dyads

Understanding the catalytic mechanism will provide insights into AIG1's substrate specificity for FAHFAs with specific branching patterns and help in developing potential inhibitors for functional studies .

What is the significance of AIG1's reactivity with fluorophosphonate probes in relation to its enzymatic mechanism?

The observed reactivity of AIG1 with fluorophosphonate (FP) probes provides important mechanistic insights:

• FP compounds typically react with active site serine or threonine residues in hydrolases

• The time-dependent, irreversible labeling suggests a covalent mechanism

• Competition experiments with FP-alkyne blocking FP-Rh labeling confirm specificity

• This reactivity pattern is consistent with AIG1's function as a FAHFA hydrolase

• The FP-reactivity can be exploited for activity-based protein profiling in complex proteomes

These findings suggest methodological approaches for identifying and characterizing novel hydrolases related to AIG1 through activity-based protein profiling techniques .