PP2A dephosphorylates p-RHO to RHO

Stable Identifier
R-HSA-74948
Type
Reaction [transition]
Species
Homo sapiens
Compartment
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Protein phosphatase 2A removes the phosphates from phosphorylated rhodopsin (p MII) and phosphorylated opsin (p-RHO) (Fowles et al. 1989, Palczewski et al. 1989a,b). A Ca2+ dependent opsin phosphatase is also present (Kutuzov & Bennett 1996). Serine/threonine protein phosphatases with EF hands (PPEF1 and 2) that share homology with Drosophila retinal degeneration C (rdgC) are expressed in retina and may be responsible (Huang & Honkanen 1998), there is no evidence for a physiological role in dephosphorylating rhodopsin. Once dephosphorylated, RHO can once again bind the chromophore 11 cis retinal (11cRAL), in readiness for the next photon response. Arrestin (S-antigen or SAG, Yamaki et al. 1988) binds to and sterically caps MII, preventing PPEF1 from dephosphorylating it.

Literature References
PubMed ID Title Journal Year
2550422 Regulation of rhodopsin dephosphorylation by arrestin.

Palczewski, K, McDowell, JH, Jakes, S, Ingebritsen, TS, Hargrave, PA

J Biol Chem 1989
8706659 Calcium-activated opsin phosphatase activity in retinal rod outer segments

Kutuzov, MA, Bennett, N

Eur. J. Biochem. 1996
9430683 Molecular cloning, expression, and characterization of a novel human serine/threonine protein phosphatase, PP7, that is homologous to Drosophila retinal degeneration C gene product (rdgC)

Huang, X, Honkanen, RE

J. Biol. Chem. 1998
11713293 Normal light response, photoreceptor integrity, and rhodopsin dephosphorylation in mice lacking both protein phosphatases with EF hands (PPEF-1 and PPEF-2)

Ramulu, P, Kennedy, M, Xiong, WH, Williams, J, Cowan, M, Blesh, D, Yau, KW, Hurley, JB, Nathans, J

Mol. Cell. Biol. 2001
3164688 The sequence of human retinal S-antigen reveals similarities with alpha-transducin.

Yamaki, K, Tsuda, M, Shinohara, T

FEBS Lett 1988
2540796 The catalytic subunit of phosphatase 2A dephosphorylates phosphoopsin.

Palczewski, K, Hargrave, PA, McDowell, JH, Ingebritsen, TS

Biochemistry 1989
2558719 Interplay of phosphorylation and dephosphorylation in vision: protein phosphatases of bovine rod outer segments.

Fowles, C, Akhtar, M, Cohen, P

Biochemistry 1990
Participants
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Catalyst Activity
Catalyst Activity
Title
protein serine/threonine phosphatase activity of PPEF1:Mg2+ [cytosol]
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Activity
This event is regulated
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