May play a role as a localized scaffold for the assembly of a multiprotein signaling complex and as mediator of the trafficking of its binding partners at specific subcellular location in neurons (By similarity). Through complex formation with NSG1, GRIA2 and STX12 controls the intracellular fate of AMPAR and the endosomal sorting of the GRIA2 subunit toward recycling and membrane targeting (By similarity). Interacts with EFNB3, GRIA2, GRIA3, GRIPAP1/GRASP1, PPFIA1, PPFIA4, FRAS1, PTPRF, liprins-alpha and the C-terminal tail of PRLHR. Can form homomultimers or heteromultimers with GRIP2 (By similarity). Interacts with EFNB1, EPHA7, EPHB2, KIF5A, KIF5B and KIF5C. Forms a ternary complex with GRIA2 and CSPG4. Interacts with ATAD1 in an ATP-dependent manner. ATAD1-catalyzed ATP hydrolysis disrupts binding to ATAD1 and to GRIA2 and leads to AMPAR complex disassembly. Interacts with SLC30A9 and PLCD4. Interacts with BUD23 (By similarity). Forms a complex with NSG1, GRIA2 and STX12; controls the intracellular fate of AMPAR and the endosomal sorting of the GRIA2 subunit toward recycling and membrane targeting. Interacts with NSG1 (By similarity). Membrane-associated with vesicles, peri-Golgi complexes and endoplasmic reticulum. Enriched in postsynaptic plasma membrane and postsynaptic densities. Expressed in brain. Isoform 2 is the major isoform in brain. Expressed in oligodendrocyte lineage cells. Detected in early development between postnatal days 3 (P3) and P8 and decreased from P14 in forebrain and cerebellum. PDZ 6 mediates interaction with the PDZ recognition motif of EFNB1 and EPHB2 and with the C-terminus of PPFIA1 and PPFIA4. PDZ 4 and PDZ 5 mediate interaction with the C-terminus of GRIA2 and GRIA3. PDZ 4, PDZ 5 and PDZ 6 mediate homomultimers. PDZ 7 mediates interaction with PDZ domain of GRASP1. PDZ 6 mediates interaction with the C-terminal of liprins-alpha. PDZ 1, PDZ 2 and PDZ 3 mediate interaction with the PDZ-binding motif of FRAS1. PDZ 4 and PDZ 5 mediate interaction with PRLHR (By similarity). PDZ 7 domain binds CSPG4. Palmitoylation of isoform 2. Major isoform. May be due to exons 2, 10 and 11 skipping.