9.A.14.20.1
The Ocular albinism type 1 gene product, OA1, or G-protein coupled receptor 143 (GPR143) of 404 aas and 7 established TMSs (Sone and Orlow 2007).  OA1 (GPR143) is a pigment cell-specific intracellular glycoprotein that is mutated in patients with ocular albinism type 1, the most common form of ocular albinism. Its cellular localization appears to be endolysosomal and melanosomal.  It is a receptor for tyrosine, L-DOPA and dopamine. Binding of L-DOPA stimulates Ca²⁺ influx into the cytoplasm, increases secretion of the neurotrophic factor SERPINF1 and relocalizes beta arrestin at the plasma membrane; this ligand-dependent signaling occurs through a G(q)-mediated pathway in melanocytic cells. Its activity is mediated by G proteins which activate the phosphoinositide signaling pathway. It also plays a role as an intracellular G protein-coupled receptor involved in melanosome biogenesis, organization and transport (Palmisano et al. 2008; Giordano et al. 2009).