Display Settings:

Format

Send to:

Choose Destination
We are sorry, but NCBI web applications do not support your browser and may not function properly. More information
Proc Natl Acad Sci U S A. 1998 Oct 13;95(21):12197-201.

Identification of the binding site for Gqalpha on its effector Bruton's tyrosine kinase.

Author information

  • 1Department of Physiology, Cornell University Medical College, 1300 York Avenue, New York, NY 10021, USA.

Abstract

Heterotrimeric G proteins and tyrosine kinases are two major cellular signal transducers. Although G proteins are known to activate tyrosine kinases, the activation mechanism is not clear. Here, we demonstrate that G protein Gqalpha binds directly to the nonreceptor Bruton's tyrosine kinase (Btk) to a region composed of a Tec-homology (TH) domain and a sarcoma virus tyrosine kinase (Src)-homology 3 (SH3) domain both in vitro and in vivo. Only active GTP-bound Gqalpha, not inactive GDP-bound Gqalpha, can bind to Btk. Mutations of Btk that disrupt its ability to bind Gqalpha also eliminate Btk stimulation by Gqalpha, suggesting that this interaction is important for Btk activation. Remarkably, the structure of this TH (including a proline-rich sequence) -SH3 fragment of the Btk family of tyrosine kinases shows an intramolecular interaction. Furthermore, the crystal structure of the Src family of tyrosine kinases reveals that the intramolecular interaction of SH3 and its ligand is the major determining factor keeping the kinase inactive. Thus, we propose an activation model that entails binding of Gqalpha to the TH-SH3 region, thereby disrupting the TH-SH3 intramolecular interaction and activating Btk.

PMID:
9770463
[PubMed - indexed for MEDLINE]
PMCID:
PMC22808
Free PMC Article

Images from this publication.See all images (4)Free text

Figure 1
Figure 2
Figure 3
Figure 4
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Write to the Help Desk