Required for perception of chronic pain through NMDA receptor signaling. Regulates surface expression of NMDA receptors in dorsal horn neurons of the spinal cord. Interacts with the cytoplasmic tail of NMDA receptor subunits as well as inward rectifying potassium channels. Involved in regulation of synaptic stability at cholinergic synapses. Part of the postsynaptic protein scaffold of excitatory synapses (By similarity). Interacts through its PDZ domains with NETO1 (By similarity). Interacts with NOS1/nNOS through second PDZ domain (By similarity). Interacts with KCNJ2/Kir2.1 (via C-terminus) through one of its PDZ domains (PubMed:15304517). Interacts with KCNJ4 (By similarity), Interacts with FRMPD4 (via C-terminus) (PubMed:19118189). Interacts with LRFN1, LRFN2 and LRFN4 (PubMed:16630835). Interacts with FASLG (PubMed:19807924). Interacts with KCNJ4 (By similarity). Interacts with ADAM22 (By similarity). Interacts with DGKI (via PDZ-binding motif) (By similarity). Concentrated in soma and postsynaptic density of a subset of neurons. An N-terminally truncated L27 domain is predicted in isoform 2 at positions 1 through 27. Palmitoylation of isoform 1 is not required for targeting to postsynaptic density. Belongs to the MAGUK family.