Photoreceptor phosphodiesterase: interaction of inhibitory gamma subunit and cyclic GMP with specific binding sites on catalytic subunits.

Journal Article (Journal Article)

The photoreceptor phosphodiesterase (PDE6) is the central effector enzyme in the phototransduction cascade of photoreceptor cells. It is the only known PDE isoform the activity of which is regulated by interaction with a heterotrimeric G protein. The rod PDE6 holoenzyme is a tetrameric protein consisting of two large catalytic alpha and beta subunits and two small gamma subunits, which serve as potent inhibitors of PDE6. In dark-adapted photoreceptors, the gamma subunits maintain PDE6 activity at a low level. When exposed to light the visual pigment rhodopsin activates the retinal G protein, transducin, leading to release of the inhibitory action of the gamma subunits. In addition to the active sites where cGMP is hydrolyzed, the alpha and beta catalytic subunits have high-affinity, noncatalytic cGMP binding sites. These noncatalytic sites do not directly regulate cGMP catalysis at the active site, but rather can modulate the affinity with which the gamma subunits bind to the catalytic subunits. This article describes a number of experimental approaches that have recently been developed for studying the interactions between catalytic and inhibitory subunits of PDE6, as well as the dynamics of cGMP binding to and dissociation from the PDE6 noncatalytic sites.

Full Text

Duke Authors

Cited Authors

  • Artemyev, NO; Arshavsky, VY; Cote, RH

Published Date

  • January 1998

Published In

Volume / Issue

  • 14 / 1

Start / End Page

  • 93 - 104

PubMed ID

  • 9500861

International Standard Serial Number (ISSN)

  • 1046-2023

Digital Object Identifier (DOI)

  • 10.1006/meth.1997.0568


  • eng

Conference Location

  • United States