The inhibitory subunit (PDEγ) of the cGMP phosphodiesterase (PDEαβγ2) in rod outer segments (ROS) realizes its regulatory role in phototransduction by inhibition of PDEαβ catalytic activity. The photoreceptor G-protein, transducin, serves as a transducer from the receptor (rhodopsin) to the effector (PDE) and eliminates the inhibitory effect of PDEγ by direct interaction with PDEγ. Our previous study [Udovichenko, Cunnick, Gonzalez and Takemoto (1994) J. Biol. Chem. 269, 9850–9856] has shown that PDEγ is a substrate for protein kinase C (PKC) from ROS and that phosphorylation by PKC increases the ability of PDEγ to inhibit PDEαβ catalytic activity. Here we report that transducin is less effective in activation of PDEαβ(γp)2 (a complex of PDEαβ with phosphorylated PDEγ, PDEγp) than PDEαβγ2. PDEγp also increases the rate constant of GTP hydrolysis of transducin (from 0.16 s-1 for non-phosphorylated PDEγ to 0.21 s-1 for PDEγp). These data suggest that phosphorylation of the inhibitory subunit of PDE by PKC may regulate the visual transduction cascade by decreasing the photoresponse.
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July 1996
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Research Article|
July 01 1996
Protein kinase C in rod outer segments: effects of phosphorylation of the phosphodiesterase inhibitory subunit
Igor P. UDOVICHENKO;
Igor P. UDOVICHENKO
1Department of Biochemistry, Kansas State University, Manhattan, KS 66506, U.S.A.
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Jess CUNNICK;
Jess CUNNICK
1Department of Biochemistry, Kansas State University, Manhattan, KS 66506, U.S.A.
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Karen GONZALEZ;
Karen GONZALEZ
1Department of Biochemistry, Kansas State University, Manhattan, KS 66506, U.S.A.
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Alexander YAKHNIN;
Alexander YAKHNIN
1Department of Biochemistry, Kansas State University, Manhattan, KS 66506, U.S.A.
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Dolores J. TAKEMOTO
Dolores J. TAKEMOTO
*
*To whom correspondence should be addressed.
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Publisher: Portland Press Ltd
Received:
January 05 1996
Accepted:
February 20 1996
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 1996
1996
Biochem J (1996) 317 (1): 291–295.
Article history
Received:
January 05 1996
Accepted:
February 20 1996
Citation
Igor P. UDOVICHENKO, Jess CUNNICK, Karen GONZALEZ, Alexander YAKHNIN, Dolores J. TAKEMOTO; Protein kinase C in rod outer segments: effects of phosphorylation of the phosphodiesterase inhibitory subunit. Biochem J 1 July 1996; 317 (1): 291–295. doi: https://doi.org/10.1042/bj3170291
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