Seems to act as a scaffold molecule at synaptic junctions by assembling neurotransmitter receptors and cell adhesion proteins (By similarity). Plays a role in nerve growth factor (NGF)-induced recruitment of RAPGEF2 to late endosomes and neurite outgrowth (By similarity). May play a role in regulating activin-mediated signaling in neuronal cells (By similarity). Enhances the ability of PTEN to suppress AKT1 activation (PubMed:10760291). Plays a role in receptor-mediated clathrin-dependent endocytosis which is required for ciliogenesis (By similarity). Interacts (via its WW domains) with DRPLA (PubMed:9647693). Interacts (via its second PDZ domain) with PTEN (via unphosphorylated C-terminus); this interaction diminishes the degradation rate of PTEN (PubMed:10760291, PubMed:11707428). Interacts (via guanylate kinase domain) with DLGAP1 (By similarity). Interacts (via the PDZ domains) with GRIN2A, GRID2 and NLGN1 (By similarity). Interacts with CTNND2, CTNNB1, MAGUIN-1, ACVR2A, SMAD2 and SMAD3 (By similarity). Part of a complex consisting of AIP1, ACVR2A, ACVR1B and SMAD3 (By similarity). May interact with HTR2A (By similarity). Interacts with IGSF9, RAPGEF2 and HTR4 (By similarity). Identified in a complex with ACTN4, CASK, IQGAP1, NPHS1, SPTAN1 and SPTBN1 (By similarity). Found in a complex, at least composed of KIDINS220, MAGI2, NTRK1 and RAPGEF2; the complex is mainly formed at late endosomes in a NGF-dependent manner (By similarity). Interacts with RAPGEF2; the interaction occurs before or after nerve growth factor (NGF) stimulation (By similarity). Interacts (via PDZ domain) with KIDINS220 (via C-terminal domain) (By similarity). Interacts with DDN (PubMed:16464232). Interacts with DLL1 (By similarity). Found in a complex with IGSF9B and NLGN2; the interaction with IGSF9B is mediated via the PDZ 5 and PDZ 6 domains, while the interaction with NLGN2 is mediated via the WW1, WW2 and PDZ2 domains (PubMed:23751499). Interacts (via PDZ 6 domain) with USH1G (via SAM domain); the interaction is triggered by phosphorylation of USH1G by CK2 and negatively regulates MAGI2-mediated endocytosis (PubMed:24608321). Localized diffusely in the cytoplasm before nerve growth factor (NGF) stimulation. Recruited to late endosomes after NGF stimulation. Membrane-associated in synaptosomes (By similarity). Specifically expressed in brain. The disease is caused by variants affecting the gene represented in this entry. Belongs to the MAGUK family.