Postsynaptic density scaffolding protein. Binds and cross-links cytoplasmic regions of GRM1, GRM5, ITPR1, DNM3, RYR1, RYR2, SHANK1 and SHANK3. By physically linking GRM1 and GRM5 with ER-associated ITPR1 receptors, it aids the coupling of surface receptors to intracellular calcium release. May also couple GRM1 to PI3 kinase through its interaction with AGAP2. Isoform 1 regulates the trafficking and surface expression of GRM5. Isoform 3 acts as a natural dominant negative, in dynamic competition with constitutively expressed isoform 1 to regulate synaptic metabotropic glutamate function. Isoform 3, may be involved in the structural changes that occur at synapses during long-lasting neuronal plasticity and development. Interacts with IFT57. Interacts with OPHN1. Isoform 1 encodes a coiled-coil structure that mediates homo- and heteromultimerization. Belongs to the Homer family. 3 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.
Cellular Component: postsynaptic membrane; costamere; cell soma; axon; apical part of cell; excitatory synapse; dendritic shaft; Z disc; cell junction
Molecular Function: identical protein binding; metabotropic glutatmate receptor binding; protein heterodimerization activity; type 5 metabotropic glutamate receptor binding; protein complex scaffold
Biological Process: skeletal muscle contraction; response to nicotine; circadian rhythm; synaptic transmission; chemical homeostasis within a tissue; positive regulation of signal transduction; behavioral response to cocaine; metabotropic glutamate receptor, phospholipase C activating pathway; skeletal muscle fiber development; positive regulation of calcium ion transport; response to calcium ion
LTP: The number of records in which this modification site was determined using site-specific methods. SS methods include amino acid sequencing, site-directed mutagenesis, modification site-specific antibodies, specific MS strategies, etc.