GNB3 and depressive disorder: Similarly, the G- protein β3 sub-unit (GNB3) enhances signal transduction and ion transport [40], and may thus be implicated in dopaminergic and serotoninergic transmission as evidenced by studies linking polymorphisms of GNB3 gene to depression, antipsychotic medications’ efficacy and neuroleptics-associated weight gain [19,41,42].