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The βγ Subunit of Heterotrimeric G Proteins Interacts with RACK1 and Two Other WD Repeat Proteins
Journal article   Open access   Peer reviewed

The βγ Subunit of Heterotrimeric G Proteins Interacts with RACK1 and Two Other WD Repeat Proteins

Edward J Dell, Jennifer Connor, Songhai Chen, Elizabeth G Stebbins, Nikolai P Skiba, Daria Mochly-Rosen and Heidi E Hamm
The Journal of biological chemistry, Vol.277(51), pp.49888-49895
12/20/2002
DOI: 10.1074/jbc.M202755200
PMID: 12359736
url
https://doi.org/10.1074/jbc.M202755200View
Published (Version of record) Open Access

Abstract

A yeast two-hybrid approach was used to discern possible new effectors for the βγ subunit of heterotrimeric G proteins. Three of the clones isolated are structurally similar to Gβ, each exhibiting the WD40 repeat motif. Two of these proteins, thereceptor foractivatedCkinase 1 (RACK1) and the dynein intermediate chain, co-immunoprecipitate with Gβγ using an anti-Gβ antibody. The third protein, AAH20044, has no known function; however, sequence analysis indicates that it is a WD40 repeat protein. Further investigation with RACK1 shows that it not only interacts with Gβ1γ1but also unexpectedly with the transducin heterotrimer Gαtβ1γ1. Gαtalone does not interact, but it must contribute to the interaction because the apparent EC50value of RACK1 for Gαtβ1γ1is 3-fold greater than that for Gβ1γ1(0.1versus0.3 μm). RACK1 is a scaffold that interacts with several proteins, among which are activated βIIPKC and dynamin-1 (1). βIIPKC and dynamin-1 compete with Gβ1γ1and Gαtβ1γ1for interaction with RACK1. These findings have several implications: 1) that WD40 repeat proteins may interact with each other; 2) that Gβγ interacts differently with RACK1 than with its other known effectors; and/or 3) that the G protein-RACK1 complex may constitute a signaling scaffold important for intracellular responses.

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