Pxl1p, a paxillin-like protein in Saccharomyces cerevisiae, may coordinate Cdc42p and Rho1p functions during polarized growth.
Rho-family GTPases Cdc42p and Rho1p play critical roles in the budding process of the yeast Saccharomyces cerevisiae. However, it is not clear how the functions of these GTPases are coordinated temporally and spatially during this process. Based on its ability to suppress cdc42-Ts mutants when overexpressed, a novel gene PXL1 was identified. Pxl1p resembles mammalian paxillin, which is involved in integrating various signaling events at focal adhesion. Both proteins share amino acid sequence homology and structural organization. When expressed in yeast, chicken paxillin localizes to the sites of polarized growth as Pxl1p does. In addition, the LIM domains in both proteins are the primary determinant for targeting the proteins to the cortical sites in their native cells. These data strongly suggest that Pxl1p is the "ancient paxillin" in yeast. Deletion of PXL1 does not produce any obvious phenotype. However, Pxl1p directly binds to Rho1p-GDP in vitro, and inhibits the growth of rho1-2 and rho1-3 mutants in a dosage-dependent manner. The opposite effects of overexpressed Pxl1p on cdc42 and rho1 mutants suggest that the functions of Cdc42p and Rho1p may be coordinately regulated during budding and that Pxl1p may be involved in this coordination.
Gao
Xiang-Dong
XD
Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104-6058, USA.
Caviston
Juliane P
JP
Tcheperegine
Serguei E
SE
Bi
Erfei
E
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016764:Cell Polarity; D002645:Chickens; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D009154:Mutation; D051419:Paxillin; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; C492861:PXL1 protein, S cerevisiae; D051419:Paxillin; D010750:Phosphoproteins; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; C051302:RHO1 protein, S cerevisiae; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae; D020741:rho GTP-Binding Proteins