title: Identification of critical phosphorylation sites on the carboxy tail of melanopsin.
abstract: Light-activated opsins undergo carboxy-terminal phosphorylation, which contributes to the deactivation of their photoresponse. The photopigment melanopsin possesses an unusually long carboxy tail containing 37 serine and threonine sites that are potential sites for phosphorylation by a G-protein dependent kinase (GRK). Here, we show that a small cluster of six to seven sites is sufficient for deactivation of light-activated mouse melanopsin. Surprisingly, these sites are distinct from those that regulate deactivation of rhodopsin. In zebrafish, there are five different melanopsin genes that encode proteins with distinct carboxy-terminal domains. Naturally occurring changes in the same cluster of phosphorylatable amino acids provides diversity in the deactivation kinetics of the zebrafish proteins. These results suggest that variation in phosphorylation sites provides flexibility in the duration and kinetics of melanopsin-mediated light responses.
authors.affiliation: Department of Biological Sciences, University of Maryland, Baltimore County , Baltimore, Maryland 21250, United States.
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Blasic
authors.forename: Vanessa
authors.initials: V
authors.lastname: Matos-Cruz
authors.forename: Devyani
authors.initials: D
authors.lastname: Ujla
authors.forename: Evan G
authors.initials: EG
authors.lastname: Cameron
authors.forename: Samer
authors.initials: S
authors.lastname: Hattar
authors.forename: Marnie E
authors.initials: ME
authors.lastname: Halpern
authors.forename: Phyllis R
authors.initials: PR
authors.lastname: Robinson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D057809:HEK293 Cells; D006801:Humans; D007700:Kinetics; D008027:Light; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family; D009154:Mutation; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D017299:Rod Opsins / Q000235:genetics / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*; D000099210:Melanopsin
chemical_list: D017299:Rod Opsins; D029961:Zebrafish Proteins; D000099210:Melanopsin