SORCS2 Antibody

What is SorCS2 and why is it important in neuroscience research?

SorCS2 is a type I transmembrane glycoprotein receptor belonging to the mammalian Vps10p (vacuolar protein-sorting 10 protein) family. This protein is predominantly expressed in the brain, especially during development, though it is also found in kidney, lung, testis, and heart tissue . The significance of SorCS2 in neuroscience stems from its role in:

• Neuronal development and survival

• Synaptic plasticity regulation

• Neurotransmitter release

• Protein trafficking in neuronal cells

• Potential involvement in neurodegenerative disorders like Alzheimer's disease

SorCS2 functions as a sorting receptor that maintains cell surface expression of neuronal proteins, including the neuronal amino acid transporter EAAT3, which facilitates neuronal protection against oxidative stress .

What are the structural characteristics of SorCS2 protein that researchers should consider when selecting antibodies?

Human SorCS2 is synthesized as a 1159 amino acid (aa) prepro form with:

• 50 aa signal sequence

• Potential furin-type proteolytic processing site at aa 119

• 959 aa extracellular/lumenal domain (ECD)

• 21 aa transmembrane domain

• 60 aa cytoplasmic domain

The ECD contains:

• An imperfect leucine-rich repeat (LRR)

• A Vps10p domain essential for ligand binding

• Six BNR repeats

• A single PKD domain

When selecting antibodies, researchers should consider epitope location relative to these domains, as they affect protein-protein interactions and subcellular trafficking. The mature SorCS2 protein has a calculated molecular weight of approximately 128 kDa, though it often appears at 120-140 kDa in Western blots due to post-translational modifications .

Which experimental applications are most commonly validated for SorCS2 antibodies?

Based on the available data, SorCS2 antibodies have been validated for the following applications:

For optimal results, researchers should determine specific dilutions for each application and sample type, as recommended by manufacturers .

What is known about the expression pattern of SorCS2 in different tissues?

SorCS2 shows a distinct expression pattern across tissues:

• Brain: Highest expression, with particular enrichment in the CA2 region of the hippocampus

• Kidney: Moderate expression, particularly in the medulla

• Other tissues: Lower expression detected in lung, testis, and heart

Within the brain, immunohistochemical studies reveal:

• SorCS2 localizes to neuronal cell bodies and dendrites rather than axons

• Co-localization with the postsynaptic marker PSD-95 but not with the presynaptic marker Bassoon

• Expression in a subset of medium spiny neurons in the striatum

This expression pattern is important for designing experiments and interpreting results, particularly when studying neuronal function or neurodegenerative conditions.

How should researchers optimize co-immunoprecipitation protocols when studying SorCS2 interactions with binding partners?

For successful co-immunoprecipitation studies involving SorCS2:

• Lysis buffer optimization:

  • Use mild detergents (0.5-1% NP-40 or Triton X-100)

  • Include protease inhibitors to prevent degradation

  • Add phosphatase inhibitors if studying phosphorylation-dependent interactions

• Immunoprecipitation strategy:

  • For SorCS2-NR2A interactions, both approaches work: immunoprecipitate with anti-SorCS2 and probe for NR2A, or immunoprecipitate with anti-NR2A and probe for SorCS2

  • Negative controls are essential: use tissue/cells with deficient SorCS2 expression or non-immune IgG

• Antibody selection:

  • Choose antibodies raised against epitopes that don't interfere with protein-protein interaction domains

  • Monoclonal antibodies often provide more consistent results for co-IP experiments

• Washing conditions:

  • Use sufficient washing steps to reduce background

  • Balance between stringency and preservation of interactions

The Mazella et al. and Rohe et al. approaches referenced in search result provide established methodologies for studying VPS10P domain receptor interactions.

What are the critical technical considerations when using SorCS2 antibodies for immunohistochemistry in brain tissue?

Immunohistochemical detection of SorCS2 in brain tissues requires careful optimization:

• Tissue preparation:

  • For fresh-frozen sections: perfusion fixation yields superior results

  • For paraffin-embedded sections: heat-induced epitope retrieval is critical using Antigen Retrieval Reagent-Basic

• Antibody incubation:

  • Overnight incubation at 4°C generally provides optimal signal-to-noise ratio

  • Concentration optimization: ~3-15 μg/mL depending on tissue type and antibody

• Detection systems:

  • For chromogenic detection: HRP-DAB systems work well with anti-sheep secondary antibodies

  • For fluorescent detection: NorthernLights 557-conjugated secondary antibodies provide good results with counterstaining using DAPI

• Critical controls:

  • Include non-immune IgG controls to establish specificity

  • Use tissue from SorCS2-deficient animals when available

  • Co-staining with neuronal markers helps confirm cell-type specificity (PCP4 for CA2 neurons)

• Signal interpretation:

  • Normal SorCS2 staining appears diffuse in neuronal cell bodies and processes

  • In disease states (e.g., Huntington's), SorCS2 shows altered distribution with perinuclear clusters and reduced process staining

How do SorCS2 expression and localization change in neurodegenerative disease models?

Research on SorCS2 in neurodegenerative conditions reveals significant changes:

These findings suggest SorCS2 trafficking defects may contribute to neurodegenerative pathology, potentially through disruption of its role in regulating surface expression of important neuronal proteins like EAAT3 and NR2A .

What is known about the structural basis of SorCS2-NGF interactions and how can this be studied experimentally?

The SorCS2-NGF interaction has been characterized through crystallography and biophysical approaches:

• Structural features:

  • SorCS2 forms cross-braced homodimers that can bind two NGF dimers in a 2:4 stoichiometry

  • The β-propeller domain of SorCS2 serves as the primary ligand binding platform

  • Both chains of the NGF dimer interact exclusively with the top face of the SorCS2 β-propeller

• Experimental approaches to study these interactions:

  • X-ray crystallography: Has revealed the detailed structure of SorCS2-NGF complex

  • Biophysical binding assays: Show that NGF, proNGF, and proBDNF all bind at the same site on SorCS2

  • Site-directed mutagenesis: Can be used to confirm key residues involved in the interaction

  • Surface plasmon resonance: For measuring binding kinetics and affinities

• Functional significance:

  • SorCS2 shows substantial structural plasticity, adopting altered conformations upon ligand binding

  • The C-terminal membrane-proximal domain with an RNA recognition motif fold locks the dimer in an intermolecular head-to-tail interaction

This structural information provides a foundation for the design of experiments targeting specific domains or interactions, potentially leading to therapeutic approaches for neurological disorders involving aberrant neurotrophin signaling.

What experimental approaches are most effective for studying SorCS2-mediated protein trafficking?

To investigate SorCS2's role in protein trafficking, researchers can employ several complementary approaches:

• Proteomics strategies:

  • Unbiased quantitative label-free mass spectrometry analysis of neuronal cell surface proteins from wild-type versus SorCS2-knockout neurons

  • This approach previously identified EAAT3 as a SorCS2 cargo

• Subcellular fractionation:

  • Separate cellular compartments (P2 synaptosomal, P3 intracellular vesicle fractions)

  • Western blot analysis of fractions to track protein distribution

  • Quantify cargo proteins (e.g., EAAT3) in each fraction

• Immunocytochemical approaches:

  • Co-localization studies with compartment markers:

    • Rab5 for early endosomes

    • Rab11 for recycling endosomes

  • Surface biotinylation assays to quantify plasma membrane protein levels

  • Antibody feeding assays to track internalization and recycling

• Live cell imaging:

  • Fluorescently tagged SorCS2 and cargo proteins

  • TIRF microscopy to visualize membrane trafficking events

  • FRAP (Fluorescence Recovery After Photobleaching) to measure protein mobility

• Functional readouts:

  • For EAAT3: measure cysteine uptake or glutamate transport

  • For NR2A: electrophysiological recordings of NMDA receptor currents

These methodologies have revealed that SorCS2 is enriched in early endosomes and recycling endosomes (Rab5+ and Rab11+ compartments), where it likely regulates the sorting and cell surface targeting of its cargo proteins .

How can researchers troubleshoot issues with SorCS2 detection in Western blot analysis?

Western blot detection of SorCS2 presents several challenges that researchers can address through methodological optimization:

• Sample preparation issues:

  • Problem: EAAT3 tends to form aggregates during processing

  • Solution: Use fresh samples, optimize detergent concentration, and avoid freeze-thaw cycles

• Protein aggregation:

  • Problem: SorCS2 may appear as higher molecular mass bands in addition to the monomer

  • Solution: Quantify signal intensities for both monomeric and aggregated forms separately and report total amounts

• Reducing conditions:

  • Problem: Some epitopes may be masked under certain conditions

  • Solution: Test both reducing and non-reducing conditions; Immunoblot Buffer Group 8 works well for SorCS2 detection under reducing conditions

• Antibody sensitivity:

  • Problem: Low endogenous expression levels in some tissues

  • Solution: Concentrate protein samples, use high-sensitivity detection systems, or increase antibody incubation time

• Membrane transfer efficiency:

  • Problem: Large proteins transfer poorly

  • Solution: Use PVDF membranes and longer transfer times for the ~128 kDa SorCS2 protein

• Antibody validation:

  • Problem: Non-specific bands

  • Solution: Include negative controls (SorCS2-knockout tissue) and positive controls (known expressing tissues like brain or kidney)

• Recommended protocol elements:

  • Sample Buffer: Laemmli with 5% β-mercaptoethanol

  • Gel: 7.5% or 4-12% gradient

  • Transfer: Wet transfer to PVDF

  • Blocking: 5% non-fat milk in TBST

  • Primary antibody: 1:500-1:1000 dilution, overnight at 4°C

  • Detection: HRP-conjugated secondary antibody with enhanced chemiluminescence

What criteria should guide selection between monoclonal and polyclonal SorCS2 antibodies for specific applications?

The choice between monoclonal and polyclonal SorCS2 antibodies should be guided by experimental requirements:

For SorCS2 specifically:

• Monoclonal antibodies like A-10 (sc-398412) work well for co-immunoprecipitation studies and can be beneficial when specific epitopes need to be targeted

• Polyclonal antibodies often provide superior results in immunohistochemistry and can detect SorCS2 across multiple species

How do species differences in SorCS2 structure affect antibody selection and experimental design?

Understanding species homology is critical for antibody selection:

• Sequence homology:

  • Within the extracellular domain (ECD), human SorCS2 shares:

    • 89% amino acid identity with mouse SorCS2

    • 88% with rat SorCS2

    • 88% with equine SorCS2

    • 79% with canine SorCS2

• Cross-reactivity considerations:

  • Human SorCS2 antibodies typically show ~20% cross-reactivity with mouse SorCS2 in direct ELISAs and Western blots

  • Species-specific antibodies may be required for high-sensitivity applications

• Epitope selection strategy:

  • Target highly conserved regions for cross-species reactivity

  • Choose species-specific regions for exclusive detection

  • Consider using antigen affinity-purified antibodies for improved specificity

• Experimental validation:

  • Always validate antibodies in your specific experimental system

  • Include appropriate positive and negative controls from relevant species

  • Consider how species differences might affect functional studies (e.g., binding partner interactions)

• Available validated antibodies by species reactivity:

  • Human-specific: Multiple options including monoclonal A-10

  • Mouse-specific: Sheep anti-mouse SorCS2 (AF4237)

  • Multi-species reactive: Several antibodies detect human, mouse, and rat SorCS2

What methodological approaches can distinguish between mature and immature forms of SorCS2 protein?

Distinguishing between mature and immature forms of SorCS2 requires specific experimental approaches:

• Biochemical characteristics:

  • SorCS2 is synthesized as a 1159 aa prepro form

  • Signal sequence (50 aa) is cleaved during translocation to ER

  • Potential furin-type proteolysis at aa 119 produces the mature 1040 aa protein

• Electrophoretic mobility:

  • Immature (unprocessed) forms generally show higher molecular weight

  • Glycosylation patterns differ between immature (high mannose) and mature (complex) forms

  • Treatment with endoglycosidases (EndoH vs. PNGaseF) can distinguish between these forms

• Subcellular fractionation:

  • Immature forms predominate in ER/Golgi fractions

  • Mature forms are found in plasma membrane and endosomal fractions

  • Combined with Western blot analysis, this can separate populations

• Pulse-chase experiments:

  • Metabolic labeling with radiolabeled amino acids

  • Chase with non-labeled medium for various time periods

  • Immunoprecipitation followed by SDS-PAGE to track maturation

• Epitope-specific antibodies:

  • Antibodies targeting the propeptide region (aa 50-119) would detect only immature forms

  • Antibodies to the mature protein region detect both forms

  • Using both types can provide a maturation index

Unlike other SorCS proteins, shedding of the SorCS2 ECD occurs very slowly and is mainly independent of the metalloproteinase TACE/ADAM17, suggesting distinct processing mechanisms that may impact experimental detection .

How can SorCS2 antibodies be used to investigate neurodegenerative disease mechanisms?

SorCS2 antibodies provide valuable tools for studying neurodegenerative disease mechanisms:

• Altered expression patterns:

  • Immunohistochemistry in human HD brain tissue shows decreased SorCS2 immunoreactivity

  • Detection of abnormal perinuclear clustering in surviving neurons

  • Western blot quantification of total SorCS2 levels in disease versus control tissue

• Subcellular redistribution:

  • Immunofluorescence co-localization with organelle markers shows redistribution in disease states

  • Fractionation studies can quantify shifts between membrane and cytosolic compartments

  • Live-cell imaging with tagged constructs can track dynamic changes

• Protein-protein interactions:

  • Co-immunoprecipitation studies reveal changes in SorCS2's interaction with NR2A in HD models

  • SorCS2 antibodies enable pull-down of complexes for proteomic analysis

  • Proximity ligation assays visualize altered interactions in situ

• Dysfunction in protein trafficking:

  • Surface biotinylation assays quantify reduced cell surface expression of SorCS2 cargoes

  • Antibody feeding assays track internalization/recycling defects

  • FRAP studies measure mobility changes in disease states

• Therapeutic target validation:

  • Immunoblotting to confirm target engagement of potential therapeutics

  • Restoration of normal SorCS2 localization as a therapeutic readout

  • Monitoring changes in SorCS2-cargo relationships with treatment

These approaches have revealed that SorCS2 dysfunction may contribute to neurodegenerative diseases through disrupted trafficking of crucial neuronal proteins like the glutamate receptor subunit NR2A, potentially contributing to motor deficits in conditions like Huntington's disease .

What experimental considerations are important when using SorCS2 antibodies to study the relationship between SorCS2 and amino acid transporter EAAT3?

Investigating the SorCS2-EAAT3 relationship requires careful experimental design:

• Technical challenges with EAAT3 detection:

  • EAAT3 forms aggregates during sample processing

  • Appears as both monomeric and aggregated forms in cell lysates

  • Primarily detected in aggregated form in surface fractions

  • Solution: Quantify both forms separately and report total amounts

• Co-localization studies:

  • Both proteins localize to early endosomes (Rab5+) and recycling endosomes (Rab11+)

  • Use super-resolution microscopy for more precise co-localization

  • Include appropriate controls (e.g., other membrane proteins not affected by SorCS2)

• Functional assays:

  • Measure cysteine uptake as a functional readout of EAAT3 activity

  • Compare wild-type vs. SorCS2-knockout neurons

  • Rescue experiments by reintroducing SorCS2 constructs

• Trafficking studies:

  • Surface biotinylation assays show SorCS2 maintains EAAT3 surface levels

  • Antibody feeding assays can track internalization and recycling rates

  • TIRF microscopy visualizes insertion events at the plasma membrane

• Protein-protein interaction verification:

  • Co-immunoprecipitation studies should include appropriate controls

  • Negative controls: SorCS2-knockout tissue, irrelevant IgG

  • Positive controls: known SorCS2 interaction partners

• Subcellular fractionation approaches:

  • P3 intracellular vesicle fraction shows reduced EAAT3 levels in SorCS2-knockout tissue

  • This fraction contains Rab11-positive recycling endosomes central to EAAT3 trafficking

  • Comparison between fractions provides insights into trafficking defects

These methodologies have established that SorCS2 acts as a sorting receptor that sustains cell surface expression of EAAT3, facilitating cysteine import and protecting neurons from oxidative stress .

What emerging techniques might enhance the utility of SorCS2 antibodies in neuroscience research?

Several innovative techniques show promise for advancing SorCS2 research:

• Super-resolution microscopy approaches:

  • 3D-SIM (Structured Illumination Microscopy) has already revealed SorCS2 colocalization with PSD-95 but not Bassoon

  • STORM/PALM could further resolve nanoscale distribution at synapses

  • Expansion microscopy might improve visualization of subcellular compartments

• Proximity labeling methods:

  • BioID or APEX2 fusions with SorCS2 to identify proximal interactors

  • TurboID for rapid labeling of the SorCS2 interactome in specific cellular compartments

  • Spatially-restricted enzymatic tagging to map compartment-specific interactions

• CryoEM studies:

  • Building on crystal structure data to examine SorCS2 in different conformational states

  • Visualization of SorCS2 complexes with trafficking machinery

  • Structural changes upon ligand binding in native-like environments

• Live-cell imaging innovations:

  • Photoactivatable or photoconvertible SorCS2 fusions to track trafficking dynamics

  • Fluorescent cargo sensors to monitor SorCS2-dependent sorting events

  • FRET-based biosensors to detect conformational changes or protein interactions

• Single-cell approaches:

  • Spatial transcriptomics combined with SorCS2 immunolabeling

  • Mass cytometry with SorCS2 antibodies for high-dimensional phenotyping

  • Patch-seq to correlate electrophysiological properties with SorCS2 expression

• In vivo applications:

  • Intrabodies or nanobodies derived from SorCS2 antibodies for live imaging

  • CRISPR-based tagging of endogenous SorCS2 for physiological expression levels

  • Optogenetic control of SorCS2 trafficking to probe function

These emerging technologies could significantly advance our understanding of SorCS2's dynamic roles in neuronal function and disease pathogenesis.

How might the discovery of the SorCS2-NGF complex structure inform development of more specific research tools?

The crystal structure of the SorCS2-NGF complex provides crucial insights for developing advanced research tools:

• Epitope-specific antibodies:

  • Design antibodies targeting the NGF binding site on the β-propeller domain

  • Create conformation-specific antibodies that recognize the ligand-bound state

  • Develop antibodies against the dimer interface to modulate dimerization

• Structure-guided protein engineering:

  • Create SorCS2 variants with modified ligand binding properties

  • Design dominant-negative constructs based on dimer formation mechanism

  • Engineer biosensors that report on ligand binding through conformational changes

• Peptide-based tools:

  • Develop peptide mimetics of the NGF binding regions to competitively inhibit interactions

  • Create stapled peptides to target specific SorCS2 conformations

  • Design cell-permeable peptides to disrupt specific protein-protein interactions

• Domain-specific functional studies:

  • The C-terminal membrane-proximal domain with RNA recognition motif fold is a novel target

  • This domain "locks" the dimer in head-to-tail interactions

  • Domain-specific antibodies or nanobodies could selectively modulate this function

• Improved recombinant proteins:

  • Design stabilized SorCS2 constructs for structural and biochemical studies

  • Create chimeric proteins with modified domain compositions

  • Develop tagged versions optimized for specific applications while preserving function