A peptide from the GAP-binding domain of the ras-p21 protein and azatyrosine block ras-induced maturation of Xenopus oocytes

D. L. Chung, P. Brandt-Rauf, R. B. Murphy, S. Nishimura, Z. Yamaizumi, I. B. Weinstein, M. R. Pincus

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

The ras-oncogene-encoded p21 protein causes malignant transformation of NIH 3T3 cells and maturation of Xenopus oocytes when microinjected into these cells. P21 is known to interact with GTPase activating protein (GAP) intracellularly. Residues 32-45 of p21 have been implicated in interacting with GAP. In a previous study, we demonstrated that a synthetic peptide containing residues 35-47 from the GAP-binding region of p21 could block in vivo the effects of oncogenic p21 protein. It has also been found that an antibiotic, azatyrosine, blocks ras-initiated cell transformation. We now demonstrate that both of these agents inhibit the ras-p21 protein-induced maturation of Xenopus oocytes in a dose-related manner when microinjected into oocytes. The effects of each of these agents is specific. Both agents block insulin-induced maturation of oocytes, a process which is known to involve activation of endogenous normal p21 protein. On the other hand, neither agent inhibited oocyte maturation induced by progesterone, which is known to initiate oocyte maturation by ras-independent pathways. The inhibitory effects of the peptide were not mimicked by a control peptide from the CD4 receptor protein. Furthermore, the effect of azatyrosine was not mimicked by L-tyrosine. These results suggest that both the peptide and azatyrosine have potent anti-ras effects intracellularly.

Original languageEnglish
Pages (from-to)1373-1378
Number of pages6
JournalAnticancer Research
Volume11
Issue number4
StatePublished - 1991
Externally publishedYes

Keywords

  • Afatyrosine
  • GAP-binding domain
  • Maturation
  • Xenopus oocytes
  • ras-p21 protein

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