p190-B, a new member of the Rho GAP family, and Rho are induced to cluster after integrin cross-linking.
p120GAP 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 alpha 5 beta 1 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-beta 1 or anti-alpha 5 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.
Laboratory of Developmental Biology, NIDR, National Institutes of Health, Bethesda, Maryland 20892-4370, USA.
P D
PD
Burbelo
S
S
Miyamoto
A
A
Utani
S
S
Brill
K M
KM
Yamada
A
A
Hall
Y
Y
Yamada
D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D005353:Fibronectins / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D006801:Humans; D016023:Integrins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D012097:Repressor Proteins; D017386:Sequence Homology, Amino Acid; D020742:rhoA GTP-Binding Protein
C074560:ARHGAP35 protein, human; C513043:ARHGAP5 protein, human; D005353:Fibronectins; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D016023:Integrins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D011506:Proteins; D012097:Repressor Proteins; D019204:GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein