Neuronal cell surface protein that may be involved in cell recognition and cell adhesion. May mediate intracellular signaling. The laminin G-like domain 1 binds to NXPH1. Interacts with PATJ (By similarity). Interacts with CBLN1, CBLN2 and, less avidly, with CBLN4 (PubMed:22220752, PubMed:21410790). Isoforms alpha 2C bind to alpha-dystroglycan (By similarity). Interacts (via Laminin G-like 1 domain) with IGSF21 (Ig-like 1 domain) in a trans-interaction manner (PubMed:28864826).