Table 1.

Expression and Function of Opsins in Melanocytes.

Opsin	Species	Potential Effect	Reference
OPN1	Mouse	Not shown	[146]
	Human	Not shown	[127,129]
OPN2	Mouse	Mediate UVA-induced immediate pigment darkening	[126,135,147]
		Regulate clock genes and melanogenesis responding to white light
	Human	Mediate UVR-induced early melanin synthesis	[127,128,129]
OPN3	Human	Sense blue light and regulate long-lasting hyperpigmentation	[129,130,131,132,133]
		Negatively regulate pigmentation through interaction with MC1R
		Regulate the survival of melanocytes
OPN4	Mouse	Mediate UVA-induced immediate pigment darkening	[146,147,148]
		Regulate clock genes and melanogenesis responding to white light
		Mediate UVA-related proliferation and apoptosis
		Mediate thermal activation of clock genes
	Human	Photoreceptor of blue light	[124]
OPN5	Mouse	Local circadian photoentrainment	[145]
	Human	Regulate UVR-induced melanogenesis	[129,130]