VSIG10L2

Model summary

A cell-surface adhesion and signaling receptor that presents a tandem array of immunoglobulin-like modules capped by a fibronectin type III domain to mediate high-avidity heterophilic binding. By clustering at the plasma membrane and within platelet alpha granule membranes, it organizes adhesive contacts and initiates downstream signaling pathways that coordinate cell communication and adhesion-dependent responses.

Predicted Gene Ontology terms

1. 01

   I begin by dissecting the InterPro architecture and its order along the sequence.

   The N-terminus carries IPR060172 (VSIG10L2, N-terminal immunoglobulin-like domain, residues 37–145), which is elaborated by multiple immunoglobulin subtype annotations: IPR003599 (Immunoglobulin domain subtype, residues 41–142) and IPR003598 (Immunoglobulin subtype 2, residues 47–129). Immediately downstream, the extracellular region continues with a tandem array of Ig-like modules: IPR013783 (Immunoglobulin-like fold, residues 145–242) and IPR036179 (Immunoglobulin-like domain superfamily, residues 154–243) encompass the first Ig-like block; a second Ig-like block is supported by IPR013783 (Immunoglobulin-like fold, residues 251–336) and IPR036179 (Immunoglobulin-like domain superfamily, residues 257–331). A third Ig-like block is indicated by IPR013783 (Immunoglobulin-like fold, residues 339–418). Mid-protein, an additional Ig-like module appears (IPR007110, Immunoglobulin-like domain, residues 404–485), followed by a dense cluster near the membrane-proximal region: IPR013783 (Immunoglobulin-like fold, residues 501–596), IPR036179 (Immunoglobulin-like domain superfamily, residues 500–601), and IPR007110 (Immunoglobulin-like domain, residues 501–593). This succession of Ig-like domains is capped by a fibronectin type III module: IPR036116 (Fibronectin type III superfamily, residues 594–694) and IPR003961 (Fibronectin type III, residues 598–699), which often follows Ig arrays in cell-adhesion receptors. The overall extracellular architecture is consolidated by IPR052598 (Immunoglobulin superfamily CEA-related, residues 16–372), signaling membership in the CEA-related IgSF family that specializes in heterophilic adhesion and immune modulation.

2. 02

   This modular extracellular scaffold—multiple Ig-like domains followed by a fibronectin type III module—creates a high-avidity, multivalent binding surface.

   Such arrays cause avid protein–protein recognition and clustering at the cell surface, which directly supports GO:0005515 protein binding as the molecular function. The presence of several Ig-like folds and a terminal FNIII domain is a hallmark of adhesion receptors that mediate heterophilic contacts rather than homotypic aggregation, aligning with heterophilic cell-cell adhesion via plasma membrane cell adhesion molecules (GO:0007157). The same architecture typically initiates outside-in and inside-out signaling cascades through receptor clustering and cytosolic tail coupling, providing a mechanistic basis for signal transduction (GO:0007165).

3. 03

   The cellular context follows from the topology.

   The extensive extracellular Ig/FNIII array implies a type I membrane receptor with an N-terminal signal peptide and a luminal/extracellular domain. Such receptors accumulate at the cell surface, consistent with the plasma membrane (GO:0005886). The annotation of platelet alpha granule membrane (GO:0031091) fits with IgSF adhesion receptors that traffic through secretory/endomembrane compartments and are stored in platelet granules; regulated exocytosis then delivers them to the platelet surface during activation. The tandem Ig/FNIII architecture is well-suited for adhesion and signaling at these membrane locales.

4. 04

   Mechanistically, the protein likely functions as a heterophilic adhesion and signaling hub.

   The N-terminal Ig-like domain (IPR060172) initiates primary binding, while subsequent Ig-like and FNIII modules stabilize and tune affinity and specificity through cooperative avidity. Clustering at the plasma membrane and platelet alpha granule membranes would nucleate signaling assemblies that regulate downstream pathways. I hypothesize that the cytosolic tail (not explicitly annotated here) couples to adaptor proteins and kinases, translating extracellular adhesion into intracellular signaling. Likely partners include other IgSF adhesion receptors and immune-modulatory molecules that co-cluster at the cell surface; in platelets, additional associations with granule cargo and activation machinery would coordinate adhesion and signaling during hemostatic responses.