Figure 2.

Melanocyte differentiation pathway dependent on MSHα and ACTH. MSHα and ACTH can both bind to MC2R. MC2R is coupled to G-protein α-s, which stimulates adenylate cyclase type I, increasing production of cAMP, hence activating PKA. PKA phosphorylates CREB1, which in turn activates the expression of MITF. MITF regulates transcription of genes coding mitochondrial ribosomal proteins through interactions with TYRP1 and MLANA.

Abbreviations: ACTH, adrenocorticotropic hormone; AMP, adenosine monophosphate; CREB1, cAMP response element-binding protein 1; MC2R, melanocortin 2 receptor; MITF, microphthalmia-associated transcription factor; MLANA, melan-A; MSHα, melanocyte-stimulating hormone α; PKA, cAMP-dependent protein kinase; TYRP1, tyrosinase-related protein 1.