Vinexin: a novel vinculin-binding protein with multiple SH3 domains enhances actin cytoskeletal organization.
Using the yeast two-hybrid system and an in vitro binding assay, we have identified a novel protein termed vinexin as a vinculin-binding protein. By Northern blotting, we identified two types of vinexin mRNA that were 3 and 2 kb in length. Screening for full-length cDNA clones and sequencing indicated that the two mRNA encode 82- and 37-kD polypeptides termed vinexin alpha and beta, respectively. Both forms of vinexin share a common carboxyl-terminal sequence containing three SH3 domains. The larger vinexin alpha contains an additional amino-terminal sequence. The interaction between vinexin and vinculin was mediated by two SH3 domains of vinexin and the proline-rich region of vinculin. When expressed, vinexin alpha and beta localized to focal adhesions in NIH 3T3 fibroblasts, and to cell-cell junctions in epithelial LLC-PK1 cells. Furthermore, expression of vinexin increased focal adhesion size. Vinexin alpha also promoted upregulation of actin stress fiber formation. In addition, cell lines stably expressing vinexin beta showed enhanced cell spreading on fibronectin. These data identify vinexin as a novel focal adhesion and cell- cell adhesion protein that binds via SH3 domains to the hinge region of vinculin, which can enhance actin cytoskeletal organization and cell spreading.
Kioka
N
N
Craniofacial Developmental Biology and Regeneration Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland 20892, USA.
Sakata
S
S
Kawauchi
T
T
Amachi
T
T
Akiyama
S K
SK
Okazaki
K
K
Yaen
C
C
Yamada
K M
KM
Aota
S
S
D016475:3T3 Cells; D000199:Actins / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002465:Cell Movement; D002645:Chickens; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D003599:Cytoskeleton / Q000502:physiology*; D018076:DNA, Complementary; D015870:Gene Expression; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000235:genetics* / Q000378:metabolism; D011817:Rabbits; D017386:Sequence Homology, Amino Acid; D013552:Swine; D014018:Tissue Distribution; D016596:Vinculin / Q000235:genetics / Q000378:metabolism*; D018909:src Homology Domains
D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D018076:DNA, Complementary; D009124:Muscle Proteins; C486523:SORBS3 protein, human; C117452:Sorbs3 protein, mouse; D016596:Vinculin