The product of this gene is a membrane-associated guanylate kinase found at the postsynaptic density in neuronal cells. It is a signaling molecule that can interact with potassium channels and receptors, as well as other signaling molecules. The protein encoded by this gene can interact with PSD-95 through its guanylate kinase domain and may be involved in clustering PSD-95 in the postsynaptic density region. The encoded protein is one of at least four similar proteins that have been found. Alternatively spliced transcript variants encoding different isoforms have been found for this gene.