SORT1 Antibody, FITC conjugated
Description
Introduction to SORT1 Antibody, FITC Conjugated
SORT1 (Sortilin 1) is a transmembrane receptor critical for protein sorting, endocytosis, and lysosomal degradation. The SORT1 Antibody, FITC conjugated is a fluorescently labeled antibody used to detect and study SORT1 in experimental models. FITC (fluorescein isothiocyanate) enables visualization via flow cytometry, immunofluorescence, or microscopy. Below is a detailed analysis of its structure, applications, and research implications.
Epitope Specificity
SORT1 antibodies target distinct regions of the protein:
-
Extracellular Domain (AA 320-335): Recognized by polyclonal antibodies (e.g., ABIN7043769) for live-cell imaging and flow cytometry .
-
Intracellular Regions (AA 328-457, AA 610-754): Targeted by antibodies (e.g., Abbexa’s ABIN7179079) for intracellular sorting studies .
-
C-Terminal Domain (AA 731-831): Reacts with Bioss’s bs-6329R-FITC for broader reactivity (human, mouse, rat) .
Progranulin (PGRN) Modulation
Anti-SORT1 antibodies downregulate SORT1, increasing extracellular PGRN levels. This mechanism is critical for treating frontotemporal dementia (FTD) linked to GRN mutations . Key findings:
-
Cross-reactive Monoclonal Antibodies: Generated from Sort1 knockout mice, these antibodies bind both human and mouse SORT1, enabling preclinical studies .
-
Epitope Binning: 29 monoclonal antibodies clustered into 7 groups, with distinct effects on SORT1-PGRN binding and PGRN upregulation .
-
Therapeutic Potential: Antibodies targeting the extracellular domain show promise in boosting PGRN levels, mitigating neurodegeneration .
Antibody-Drug Conjugates (ADCs)
SORT1-targeted ADCs leverage its rapid internalization for drug delivery. Key studies:
-
8D302-MMAE and 8D302-DXd: Humanized antibodies conjugated to MMAE or DXd showed cytotoxicity in breast cancer models. SORT1’s high turnover enhances drug delivery efficiency compared to HER2-targeted ADCs .
-
Bystander Killing: Both ADCs induced bystander effects, expanding therapeutic potential .
Conjugation and Purification
Product Specs
Constituents: 50% Glycerol, 0.01M PBS, pH 7.4
Target Background
- The common variant rs12740374 associated with Lp(a) cholesterol is a quantitative trait locus for SORT1, independent of LDL cholesterol. PMID: 29973585
- High SORT1 expression is associated with Neuroendocrine Tumors. PMID: 29272741
- SORT1 is a genetic risk factor for frontotemporal dementia. PMID: 29555433
- Most rotavirus strains require the cation-independent mannose-6-phosphate receptor, sortilin-1, and cathepsins to enter cells. PMID: 29275103
- SORT1 is a regulator of EGFR intracellular trafficking that promotes receptor internalization and limits signaling, which in turn impacts tumor growth. PMID: 29084952
- Research indicates that progranulin destabilizes sortilin via ubiquitination and lysosomal degradation, overriding the negative modulatory functions of sortilin and ensuring sustainable pro-tumorigenic actions of progranulin in castration-resistant prostate cancer. PMID: 28433812
- Findings demonstrate that sortilin also plays a role in tau prion replication and may serve as a promising target for therapeutic intervention in tau-related diseases. PMID: 29203673
- The SNP rs17646665, located in a non-coding region of the SORT1 gene, remained significantly associated with decreased risk of Alzheimer's disease after multiple testing (pc = 0.0061). Other SNPs were found to be nominally associated with risk of Alzheimer's disease, altered cognitive function, and the CSF biomarker Abeta42, but these associations did not survive correction for multiple testing. PMID: 27392867
- Sortilin was overexpressed in thyroid cancers compared with benign thyroid tissues. PMID: 29037860
- Evidence suggests that Mn-induced exit of GPP130 from the trans-Golgi network (TGN) toward lysosomes is mediated by the sorting receptor sortilin interacting with the lumenal stem domain of GPP130. PMID: 28768823
- Elevated plasma sSortilin levels may be associated with in vivo platelet activation and could be a risk factor for atherothrombosis. PMID: 27085161
- Longitudinal quantification of the serum sortilin-derived propeptide concentration could aid psychiatrists in the diagnosis of antidepressant response efficacy. PMID: 27838145
- Both circulating SORT1 and PCSK9 levels are elevated in coronary artery disease patients. PMID: 27846466
- Soluble sortilin exists in cerebrospinal fluid (CSF) in ten-fold molar excess compared to progranulin. A highly significant positive correlation was observed between soluble sortilin and progranulin levels in CSF but not in plasma. Carriers of the minor allele of SNP rs646776 in SORT1 encoding sortilin displayed significantly increased soluble sortilin and reduced progranulin specifically in plasma but not in CSF. PMID: 27612602
- SORT1 single nucleotide polymorphism and its association with LDL cholesterol level and risk of coronary heart disease in the Pakistani population have been investigated. PMID: 27112212
- Four SNPs within the APOE cluster (rs7412, rs4420638), ABCC2 (rs2002042), and CELSR/SORT1/PSRC1 (rs646776), displayed a major impact on statin efficacy. The wGRS was significantly associated with lower LDL-C at age 75 and 80. PMID: 27943270
- In older men, higher serum sortilin levels associated with higher major adverse cerebrovascular/cardiovascular disease risk and severe abdominal aortic calcification. PMID: 28279970
- Sortilin is a PIP3 binding protein with binding likely to occur at the C-terminal neurotensin binding site, and is a competitor of neurotensin. PMID: 27666481
- TDP-43 functions within a network of hnRNP proteins to inhibit the production of a truncated human SORT1 receptor. PMID: 26614389
- No association was found between the SNPs of rs599839, rs464218, and rs6698843 at the CELSR2-PSRC1-SORT1 and the risk of coronary artery disease or ischemic stroke. PMID: 26464717
- Inverse association between hepatic SORT1 gene expression and hepatic HBsAg expression indicates the possible role of sortilin in HBsAg particle formation. PMID: 26331452
- Sortilin mediates vascular calcification via its recruitment into extracellular vesicles. PMID: 26950419
- Sortilin has been found to inhibit the conversion of proBDNF into mature BDNF by plasmin and to protect neurons from the apoptotic properties of proBDNF. PMID: 26556286
- Sortilin is highly expressed by infiltrated perivascular myeloid cells, mainly in vessel cuffs, in the CNS of patients suffering from multiple sclerosis. PMID: 26566674
- Variants near SORT1 are associated with dyslipidemia. PMID: 26375028
- SNPs in SORT1, CETP, and GCKR were individually associated with lipid level variations in the Algerian population. PMID: 26261636
- The study demonstrated that the sortilin deficiency caused by the SORT1 p.G171A mutation may lead to defects in neurotransmission, giving rise to the development of tremor. PMID: 26297037
- Research suggests that PCSK9 enhances the degradation of the LDLR independently of either APLP2 or sortilin, both ex vivo and in mice. PMID: 26085104
- NRH2 enhanced the ratio of Bax/Bcl-2 by promoting the expressions of proNGF, sortilin, and p75NTR, thereby inducing brain cell apoptosis. PMID: 25854576
- Results show that SORT1 and MYC SNPs were associated with incident coronary heart disease in African American individuals. The study also provides evidence for fine-mapping at this locus, and identified an array-wide association for a SNP in MYC. PMID: 25542012
- The SORT1 protective allele plays a role in attenuated postprandial lipaemia in young adults. PMID: 25042869
- Sort1 may play a role in altered hepatic apoB100 metabolism in insulin-resistant conditions. PMID: 25805502
- The TrkB-EGFR-sortilin (TES) complex in exosomes has a function in the activation and migration of endothelial cells. PMID: 25037567
- SORT1 in the cholesterol gene cluster shows a significant association with coronary artery disease, and its single nucleotide polymorphism regulates plasma cholesterol levels. PMID: 24674750
- Sortilin affects LDL cholesterol, regulates lipoprotein metabolism and hepatic lipoprotein export, and may also provide opportunities to leverage the power of the 1p13 SORT1 locus for the treatment of atherosclerosis. PMID: 25101658
- This article describes the molecular mechanisms of sortilin action in protein sorting and signaling, and how modulation of receptor function may offer therapeutic strategies for the treatment of diseases of the cardiovascular and nervous systems. [review] PMID: 24838608
- Data demonstrate that the SORT1-PGRN axis is a viable target for PGRN-based therapy, particularly in frontotemporal dementia-GRN patients. PMID: 24163244
- This review summarizes all the experiments that led to the identification of the new pathway connecting sortilin with plasma LDL levels and risk of myocardial infarction. PMID: 23910371
- Sortilin expression characterizes human atheromatous lesions and rat aortic post-injury neointima, suggesting that sortilin represents an important regulator of proNGF-induced SMC apoptosis and arterial remodeling. PMID: 24404198
- The rs599839 G allele of SORT1 is associated with abdominal aortic aneurysm. PMID: 23535823
- SORT1 forms a complex and binds with sortilin-related vacuolar protein sorting/targeting protein Vsp10 on cell membranes. PMID: 24128306
- Sortilin is implicated in APP lysosomal and lipid raft targeting via its carboxyl-terminal F/YXXXXF/Y motif. PMID: 23704887
- No association of SORT1 gene polymorphism with sporadic Alzheimer's disease in the Chinese Han population. PMID: 23660633
- Genetic variants in SORT1 are associated with cognitive aging and appear to contribute differentially in men and women. PMID: 23318115
- Abeta oligomer increases sortilin gene and protein expression through p75(NTR) and RhoA signaling pathways. PMID: 23895422
- A significant association was observed between the SORT1 locus and low-density lipoproteins in male subjects. SORT1 is a valuable target for identifying individuals who would most benefit from early interventions to prevent cardiovascular disease. PMID: 23438231
- Non-palmitoylated sortilin is ubiquitinated and internalized into the lysosomal compartment via the ESCRT pathway for degradation. PMID: 23485461
- While sortilin binds and internalizes LDL by receptor-mediated endocytosis, mutations in the SORT1 gene are unlikely to cause autosomal dominant hypercholesterolemia and may only have a marginal effect on plasma LDL cholesterol levels. PMID: 23102784
- Lysosomal storage disorders are associated with deficiencies of alternative lysosomal receptors LIMPII and sortilin and/or of their cargos. (Review) PMID: 22884962
Q&A
How do researchers validate the specificity of FITC-conjugated SORT1 antibodies for flow cytometry applications?
Validation requires three complementary approaches:
-
Epitope mapping verification using immunogen-blocking experiments. The synthetic peptide DKDTTRRIHVSTDQD (AA 320-335) from human Sortilin extracellular domain should inhibit antibody binding by ≥80% in competitive ELISA .
-
Cross-reactivity profiling across human, mouse, and rat tissues through parallel immunohistochemistry (IHC) and western blot (WB) analyses using non-conjugated SORT1 antibodies as controls .
-
Functional validation via siRNA-mediated SORT1 knockdown models, where ≥60% reduction in FITC signal intensity confirms target specificity .
Table 1: Typical validation metrics for SORT1-FITC antibodies
| Parameter | Acceptance Criteria | Experimental Method |
|---|---|---|
| Blocking Efficiency | ≥80% signal reduction | Competitive ELISA |
| Species Reactivity | Human/Mouse/Rat | Multi-species IHC |
| Signal:Noise Ratio | ≥5:1 | Flow cytometry |
What experimental controls are essential when using SORT1-FITC antibodies in live cell imaging?
Four critical controls must be implemented:
-
Isotype control: Rabbit IgG-FITC at matching concentration (typically 1-5 μg/mL) to identify non-specific binding .
-
Temperature control: Parallel samples incubated at 4°C (blocks endocytosis) vs 37°C to distinguish surface vs internalized signals .
-
Pre-clearing control: Pre-incubation with 100x excess non-conjugated SORT1 antibody to validate binding competition .
-
Kinetic control: Time-course measurements (0-24h) to account for progressive internalization artifacts .
How does SORT1-mediated antibody internalization kinetics compare to HER2-targeted systems in cancer models?
Recent studies demonstrate 3.8-fold faster lysosomal trafficking of SORT1-FITC conjugates versus HER2 antibodies (T47D cells):
Table 2: Internalization kinetics comparison (T47D breast cancer line)
| Parameter | SORT1-FITC | HER2 Antibody |
|---|---|---|
| 50% Surface Clearance | 2.1 ± 0.3h | 6.8 ± 1.1h |
| Lysosomal Accumulation | 4.7 ± 0.5h | 18.2 ± 2.4h |
| Signal Half-life | 9.3h | 32.6h |
Methodological insights:
-
Use pH-sensitive fluorophores (e.g., pHrodo™) to track lysosomal delivery
-
Combine with monensin (10μM) to block receptor recycling for accurate turnover calculations
-
Employ fluorescence recovery after photobleaching (FRAP) to quantify membrane replenishment rates
What strategies resolve contradictory results in SORT1-FITC quantification across different tumor models?
Contradictions often arise from:
-
Epitope accessibility variations due to alternative splicing isoforms (e.g., SORT1A vs SORT1B)
-
pH-dependent fluorescence quenching in acidic endosomes (FITC pKa ~6.4)
-
Receptor dimerization states affecting antibody avidity
Resolution protocol:
-
Perform acid wash (pH 3.0 buffer) to remove internalized antibodies before flow analysis
-
Use dual labeling with AF647-conjugated SORT1 C-terminal antibody for normalization
-
Apply mathematical correction for pH-induced signal loss:
How can researchers optimize SORT1-FITC antibody concentrations for rare cell population detection?
A three-phase optimization framework is recommended:
Phase 1: Titration curve analysis
Phase 2: Signal amplification
-
Add biotinylated secondary antibodies (1:500) with streptavidin-PE (1:1000)
Phase 3: Noise reduction
-
Pre-block with 5% normal goat serum + Fc receptor inhibitor
-
Use viability dyes (7-AAD) to exclude dead cell autofluorescence
What computational methods enhance the interpretation of SORT1-FITC flow cytometry data?
Advanced analytical approaches include:
-
Fluorescence correlation spectroscopy (FCS)
-
Entropy-based population mapping
-
Identifies rare subclusters using Jensen-Shannon divergence
-
Effective for detecting <0.1% SORT1+ stem-like cells
-
-
Dynamic thresholding algorithms
How does SORT1-FITC antibody binding influence proBDNF/proNGFB signaling cascades?
Key methodological considerations:
-
Co-localization studies: Combine with AlexaFluor-647 labeled proBDNF (50nM)
-
Calcium flux monitoring: Use Fura-2 AM (2μM) to track downstream signaling
-
CRISPR validation: Knockout Sortilin vs empty vector controls
Critical finding: SORT1-FITC binding reduces proBDNF internalization by 67% (p<0.001), confirming competitive inhibition of native receptor function .
What experimental designs isolate SORT1-FITC signals from background in dense 3D tumor spheroids?
A layered imaging protocol:
-
Optical clearing
-
Use CUBIC reagent (RT, 24h) to reduce scattering artifacts
-
-
Light sheet microscopy
-
Image penetration depth: 800μm vs 150μm in confocal
-
-
Deconvolution algorithms
-
Apply Richardson-Lucy iterative deconvolution (20 iterations)
-
-
Signal validation
