Amino acid residues in the CDC25 guanine nucleotide exchange factor critical for interaction with Ras.
Previously we found that negatively charged residues at positions 62, 63, and 69 of H-Ras are involved in binding to the CDC25 guanine nucleotide exchange factor (GEF). Using site-directed mutagenesis, we have changed conserved, positively charged residues of CDC25GEF to glutamic acid. We find the nonfunctional CDC25R1374E mutant and the nonfunctional H-RasE63K mutant cooperate in suppression of the loss of CDC25 function in Saccharomyces cerevisiae. Also, peptides corresponding to residues 1364 to 1383 of CDC25GEF inhibit interaction between GEFs and H-Ras. We propose that residues 1374 of CDC25GEF and 63 of H-Ras form an ion pair and that when this ion pair is reversed, functional interaction can still occur.
Department of Biological Sciences, University of Southern California, Los Angeles 90038.
W
W
Park
R D
RD
Mosteller
D
D
Broek
D006801:Humans; D066298:In Vitro Techniques; D016297:Mutagenesis, Site-Directed; D010749:Phosphoprotein Phosphatases / Q000737:chemistry*; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry*; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D013329:Structure-Activity Relationship; D020666:ras-GRF1
D011506:Proteins; D020666:ras-GRF1; D010749:Phosphoprotein Phosphatases; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)