p190-B, a New Member of the Rho GAP Family, and Rho Are Induced to Cluster after Integrin Cross-linking

doi:10.1074/jbc.270.52.30919

p190-B, a New Member of the Rho GAP Family, and Rho Are Induced to Cluster after Integrin Cross-linking (*)

From the Laboratory of Developmental Biology, NIDR, National Institutes of Health, Bethesda, Maryland 20892-4370 and the
Medical Research Council Laboratory for Molecular Cell Biology, CRC Oncogene and Signal Transduction Group, University College London, Gower Street, London WC1E6BT, United Kingdom

^§ Present address: MRC Laboratory for Molecular Cell Biology, CRC Oncogene and Signal Transduction Group, University College London, Gower St., London WC1E6BT, United Kingdom. To whom correspondence should be addressed. Tel.: 44-71-380-7911; Fax: 44-71-380-7805.

Abstract

p120 forms distinct complexes with two phosphoproteins, p62 and p190. Here we have cloned a cDNA encoding a protein with 51% amino acid identity to p190 (hereafter designated p190-A) and have designated it p190-B. The N-terminal portion of p190-B contained several motifs characteristic of a GTPase domain, while its C terminus contained a Rho GAP domain. A recombinant Rho GAP domain polypeptide showed GAP activity for RhoA, Rac1, and G25K/CDC42Hs. Immunoprecipitation and immunofluorescence studies demonstrated that p190-B protein was expressed in a variety of cells and was localized diffusely in the cytoplasm and in fibrillar patterns that co-localized with the α⁵β¹ integrin receptor for fibronectin. Adhesion of fibronectin-coated latex beads to cells resulted in recruitment of significant amounts of p190-B and Rho to the plasma membrane beneath the site of bead binding. In contrast, beads coated with polylysine or concanavalin A were unable to recruit p190-B or Rho. Additionally, anti-β¹ or anti-α⁵ integrin antibody-coated beads were also able to recruit large amounts of p190-B and Rho. These results identify a novel second member of the p190 family and establish the existence of a novel transmembrane link between integrins and a new protein p190-B and Rho.

Footnotes

↵* This work was supported in part by the Wellcome Trust (to P. D. B.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank(TM)/EMBL Data Bank with accession number(s) U17032[GenBank].
↵¹ The abbreviations used are:

LPA

lysophosphatidic acid

GAP

GTPase activating protein.
↵² P. D. Burbelo, unpublished results.
- Received September 21, 1994.
- Revision received July 21, 1995.