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 (PubMed:9069286). 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 (PubMed:16037816). Interacts with EFNB1, EPHA7, EPHB2, EFNB3, KIF5A, KIF5C, KIF5B and the C-terminal tail of PRLHR. Forms a ternary complex with GRIA2 and CSPG4 (By similarity). Can form homomultimers or heteromultimers with GRIP2. Interacts with GRIA2, GRIA3, GRIPAP1/GRASP1, PPFIA1, PPFIA4, FRAS1, PLCD4, PTPRF and liprins-alpha. 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 (By similarity). 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 (PubMed:16037816). Interacts with NSG1 (PubMed:16037816). Membrane-associated with vesicles, peri-Golgi complexes and endoplasmic reticulum. Enriched in postsynaptic plasma membrane and postsynaptic densities. Expressed in brain, testis and retina. In brain highly expressed in the olfactory bulb, cortex and hippocampus and lower level in thalamus, cerebellum and spinal cord. In brain it is found in the perikaryon, dendrites, dendritic shafts, dendritic spines and, excitatory and inhibitory synapses of neurons. In retina, it is most abundant in the plexiform layers than in perikarya. Detected in early embryonic stage as early as E15, gradually increased throughout early development, peaked at approximately between postnatal days P6 and P8, then slightly decreased and remained relatively stable in the adult. 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 PRLHR (By similarity). 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 7 domain binds CSPG4. PDZ 6 mediates interaction with the C-terminus of liprins-alpha. PDZ 1, PDZ 2 and PDZ 3 mediate interaction with the PDZ-binding motif of FRAS1.