Seems to act as scaffold molecule at synaptic junctions by assembling neurotransmitter receptors and cell adhesion proteins (PubMed:9694864). Plays a role in nerve growth factor (NGF)-induced recruitment of RAPGEF2 to late endosomes and neurite outgrowth (PubMed:17724123). May play a role in regulating activin-mediated signaling in neuronal cells (By similarity). Enhances the ability of PTEN to suppress AKT1 activation (By similarity). Plays a role in receptor-mediated clathrin-dependent endocytosis which is required for ciliogenesis (By similarity). Interacts (via its WW domains) with DRPLA (By similarity). Interacts with CTNNB1, ACVR2A, SMAD2 and SMAD3 (By similarity). Part of a complex consisting of AIP1, ACVR2A, ACVR1B and SMAD3 (By similarity). May interact with HTR2A and IGSF9 (By similarity). Interacts with HTR4 (By similarity). Interacts (via guanylate kinase domain) with DLGAP1 (PubMed:9694864). Interacts (via PDZ domains) with GRIN2A, GRID2 and NLGN1 (PubMed:9694864, PubMed:12589829). Interacts with CTNND2 (PubMed:10080919). Interacts with MAGUIN-1 (PubMed:10207009). Interacts (via its second PDZ domain) with PTEN (via unphosphorylated C-terminus); this interaction diminishes the degradation rate of PTEN (PubMed:15951562). 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 (PubMed:17724123). Interacts with RAPGEF2; the interaction occurs before or after nerve growth factor (NGF) stimulation (PubMed:10548487). Isoform 1 interacts (via PDZ domain) with KIDINS220 isoform 2 (via C-terminal domain) (PubMed:17724123). Interacts with DDN (PubMed:16751601, PubMed:16464232). Identified in a complex with ACTN4, CASK, IQGAP1, NPHS1, SPTAN1 and SPTBN1 (PubMed:15994232). 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 (By similarity). Membrane-associated in synaptosomes. Localized diffusely in the cytoplasm before nerve growth factor (NGF) stimulation. Recruited to late endosomes after NGF stimulation. Expressed in the foot process layer of podocytes of the kidney glomeruli but not in tubules (at protein level). Expressed in the brain. Expressed during the late capillary loop stage of glomerulogenesis. First detected in junctional complexes in podocytes after their migration to the base of cells. Up-regulated upon foot process differentiation. Belongs to the MAGUK family.