Seems to play a role in the development or function of the kidney glomerular filtration barrier. Regulates glomerular vascular permeability. May anchor the podocyte slit diaphragm to the actin cytoskeleton. Plays a role in skeletal muscle formation through regulation of myoblast fusion (By similarity). Interacts with CD2AP (via C-terminal domain). Interacts with MAGI1 (via PDZ 2 and 3 domains) forming a tripartite complex with IGSF5/JAM4. Interacts with DDN; the interaction is direct. Self-associates (via the Ig-like domains). Also interacts (via the Ig-like domains) with KIRREL1/NEPH1 and KIRREL2; the interaction with KIRREL1 is dependent on KIRREL1 glycosylation. Interacts with KIRREL3. Forms a complex with ACTN4, CASK, IQGAP1, MAGI2, SPTAN1 and SPTBN1 (By similarity). Interacts with NPHS2 (PubMed:11562357). Predominantly located at podocyte slit diaphragm between podocyte foot processes. Also associated with podocyte apical plasma membrane. Specifically expressed in podocytes of kidney glomeruli. In 23-week-old embryo found in epithelial podocytes of the periphery of mature and developing glomeruli. Phosphorylated at Tyr-1193 by FYN, leading to the recruitment and activation of phospholipase C-gamma-1/PLCG1. The disease is caused by variants affecting the gene represented in this entry. Belongs to the immunoglobulin superfamily.