Molecular cloning and expression of a G25K cDNA, the human homolog of the yeast cell cycle gene CDC42.
G25K is a low-molecular-mass GTP-binding protein with a broad distribution in mammalian tissues. A cDNA clone was isolated by using oligonucleotides corresponding to the partial amino acid sequence of purified human G25K. The cDNA encodes an 191-amino-acid polypeptide containing GTP-binding consensus sequences and a putative farnesylation site at the C terminus. The sequence exhibits 50 and 70% identities to the mammalian rho and rac proteins, respectively, and an 80% identity to the Saccharomyces cerevisiae CDC42 gene product. Insect Sf9 cells infected with recombinant baculovirus vectors expressing the G25K cDNA produced a 25-kDa protein that bound GTP and was recognized by antibodies specifically reactive to G25K. G25K appears to be the human homolog of the CDC42 gene product, since expression of the G25K cDNA in S. cerevisiae suppressed both cdc42-1 and cdc24-4 temperature-sensitive lethal mutations.
Munemitsu
S
S
Department of Molecular Biology, Cetus Corporation, Emeryville, California 94608.
Innis
M A
MA
Clark
R
R
McCormick
F
F
Ullrich
A
A
Polakis
P
P
D000595:Amino Acid Sequence; D001483:Base Sequence; D002453:Cell Cycle; D003001:Cloning, Molecular / Q000379:methods; D005656:Fungal Proteins / Q000235:genetics*; D019204:GTP-Binding Proteins / Q000235:genetics*; D005800:Genes, Fungal; D006801:Humans; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D010957:Plasmids; D016133:Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D013696:Temperature; D020764:cdc42 GTP-Binding Protein; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae
D005656:Fungal Proteins; D015345:Oligonucleotide Probes; D019204:GTP-Binding Proteins; D020764:cdc42 GTP-Binding Protein; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae