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. Author manuscript; available in PMC: 2019 Mar 1.
Published in final edited form as: Cell Rep. 2018 Nov 27;25(9):2497–2509.e4. doi: 10.1016/j.celrep.2018.11.008

Figure 7. Both β-Arrestins Contribute Specifically to the Melanopsin Photocycle.

Figure 7.

Proposed melanopsin photocycle model. Active melanopsin (Ma) is photo-isomerized into activated melanopsin (Ma*), the signaling form, upon photon absorption. Phosphorylation of Ma* primes its binding by βArr2 and subse-quent deactivation (Mi*, inactive melanopsin). βArr1 would then participate in melanopsin chromophore exchange and subsequent ipRGCs resensitization. Absorption of a photon from another wavelength may photoregenerate directly the Ma* into the Ma form. Exogenous 11-cis-retinal supply rescues the desensitization observed in βarr1-deficient mice.