Subtype-specific binding of azidoanilido-GTP by purified G protein alpha subunits.

Journal Article

Azidoanilido-GTP (AA-GTP), a hydrolysis-resistant, photoreactive GTP analog, is becoming an increasingly popular tool for identifying activation of specific G proteins by receptors within native plasma membranes. Despite the use of AA-GTP as an affinity probe, surprisingly little is known regarding the ability of various G protein alpha subunits to bind this analog. To directly address this issue, we compared the ability of four purified G protein alpha subunits (Go, Gi2, Gs, and Gz) to bind AA-GTP with their ability to bind GTP gamma S, a GTP analog commonly used to characterize the GTP-binding properties of G proteins. All four G alpha subunits tested bound AA-GTP in a manner distinct from their binding of GTP gamma S. One of these proteins, Gs alpha, required millimolar levels of free Mg2+ for significant binding of AA-GTP, while Go alpha and Gi alpha 2 displayed peak AA-GTP binding at approximately 100 microM free Mg2+. The fourth G alpha subunit, Gz, bound AA-GTP very poorly relative to GTP gamma S regardless of the magnesium concentration. These results indicate that individual G protein alpha subunits differ markedly in their ability to bind AA-GTP. Use of AA-GTP to identify specific G protein-receptor interactions must therefore take into account the varied abilities of G alpha subunits to bind this analog.

Full Text

Duke Authors

Cited Authors

  • Fields, TA; Linder, ME; Casey, PJ

Published Date

  • June 7, 1994

Published In

Volume / Issue

  • 33 / 22

Start / End Page

  • 6877 - 6883

PubMed ID

  • 8204622

International Standard Serial Number (ISSN)

  • 0006-2960

Language

  • eng

Conference Location

  • United States