Microtubule-associated protein involved in membrane protein-cytoskeleton interactions. It is thought to anchor the inhibitory glycine receptor (GLYR) to subsynaptic microtubules (By similarity). Acts as a major instructive molecule at inhibitory synapses, where it also clusters GABA type A receptors (PubMed:25025157). Has also a catalytic activity and catalyzes two steps in the biosynthesis of the molybdenum cofactor. In the first step, molybdopterin is adenylated. Subsequently, molybdate is inserted into adenylated molybdopterin and AMP is released. ATP + H(+) + molybdopterin = adenylyl-molybdopterin + diphosphate adenylyl-molybdopterin + H(+) + molybdate = AMP + H2O + Mo-molybdopterin Inhibited by copper and tungsten. Cofactor biosynthesis; molybdopterin biosynthesis. Homotrimer, homodimer and homooligomer (PubMed:25025157). Interacts with SRGAP2 (via SH3 domain) (PubMed:22126966, PubMed:27373832). Interacts with GLRB (By similarity). Interacts with GABARAP (By similarity). Interacts with GABRA3 (By similarity). GABRA3 and GLRB occupy overlapping binding sites (By similarity). Interacts with ARHGAP32; IQSEC3, INSYN1 and INSYN2A (PubMed:27609886). Cytoplasmic face of glycinergic postsynaptic membranes (By similarity). Forms clusters at synapses (PubMed:25025157). Palmitoylated (PubMed:25025157). Palmitoylation is stimulated by GABA type A receptors activity (PubMed:25025157). Palmitoylation by ZDHHC12 regulates clustering at synapses (PubMed:25025157). In the N-terminal section; belongs to the MoaB/Mog family. In the C-terminal section; belongs to the MoeA family.