Inhibition of ras-induced oocyte maturation by peptides from ras-p21 and GTPase activating protein (GAP) identified as being effector domains from molecular dynamics calculations.
In the accompanying article, using molecular dynamics calculations, we found that the 66-77 and 122-138 domains in ras-p21 and the 821-827, 832-845, 917-924, 943-953, and 1003-1020 domains in GAP have different conformations in complexes of GAP with wild-type and oncogenic ras-p21. We have now synthesized peptides corresponding to each of these domains and coinjected them into oocytes with oncogenic p21, which induces oocyte maturation, or injected them into oocytes incubated with insulin that induces maturation by activating wild-type cellular ras-p21. We find that all of these peptides inhibit both agents but do not inhibit progesterone-induced maturation that occurs by a ras-independent pathway. The p21 66-77 and 122-138 peptides cause greater inhibition of oncogenic p21. On the other hand, the GAP 832-845 and 1003-1021 peptides inhibit insulin-induced maturation to a significantly greater extent. Since we have found that activated wild-type and oncogenic p21 activate downstream targets like raf differently, these GAP peptides may be useful probes for identifying elements unique to the wild-type ras-p21 pathway.
Friedman
Fred K
FK
Laboratory of Metabolism, National Cancer Institute, Bethesda, MD 20892, USA.
Chie
Lyndon
L
Chung
Denise
D
Robinson
Richard
R
Brandt-Rauf
Paul
P
Yamaizumi
Ziro
Z
Pincus
Matthew R
MR
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D004926:Escherichia coli; D020690:GTPase-Activating Proteins / Q000737:chemistry / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology; D008969:Molecular Sequence Data; D015689:Oncogene Protein p21(ras) / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D009865:Oocytes / Q000187:drug effects* / Q000254:growth & development*; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology*; D011374:Progesterone / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D016283:Proto-Oncogene Proteins p21(ras) / Q000737:chemistry / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014982:Xenopus laevis
D004791:Enzyme Inhibitors; D020690:GTPase-Activating Proteins; D007328:Insulin; D010446:Peptide Fragments; D011374:Progesterone; D015689:Oncogene Protein p21(ras); D016283:Proto-Oncogene Proteins p21(ras)