Protein kinase C in rod outer segments: Effects of phosphorylation of the phosphodiesterase inhibitory subunit

Igor P. Udovichenko, Jess Cunnick, Karen Gonzalez, Alexander Yakhnin, Dolores J. Takemoto

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

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 PDEy. Our previous study [Udovichenko, Cunnick, Gonzalez and Takemoto (1994) J. Biol. Chem. 269, 9850-9856] has shown that PDEy 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 PDEy 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.

Original languageEnglish (US)
Pages (from-to)291-295
Number of pages5
JournalBiochemical Journal
Volume317
Issue number1
DOIs
StatePublished - Jul 1 1996

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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