GPR143, also known as Ocular albinism 1 (OA1) binds L-dopamine (L-Dopa) (Lopez et al. 2008, Hiroshima et al. 2014), the precursor to the neurotransmitters dopamine, norepinephrine (noradrenaline), and epinephrine (adrenaline) collectively known as catecholamines. L-Dopa is in intermediate of melanin biosynthesis (Aroca et al. 1993, Roffler-Tarlov et al. 2013). GPR143 is present on the apical cell surface of retinal pigment epithelial cells (Lopez et al. 2008). GPR143 can associate with several Galpha subunits, Gbeta and arrestin (Schiaffino & Tacchetti 2005, Innamorati et al. 2006). Its signalling is pertussis toxin sensitive and therefore likely to be mediated by Gq (Lopez et al. 2008).