Ras-dependent maturation of Xenopus oocytes is blocked by modified peptides of GTPase activating protein (GAP)
| Autor: | Edgar P. Heimer, J. E. Scheffler, Anthony Neri, Joseph E. LoSardo, Eva Bekesi, Kathleen Prinzo |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
GTP'
GTPase-activating protein Molecular Sequence Data Xenopus Peptide GTPase Biochemistry GTP Phosphohydrolases Proto-Oncogene Proteins p21(ras) Xenopus laevis medicine Animals Insulin Amino Acid Sequence Microinjection Progesterone chemistry.chemical_classification Germinal vesicle biology GTPase-Activating Proteins Proteins biology.organism_classification Oocyte Kinetics medicine.anatomical_structure chemistry ras GTPase-Activating Proteins Oocytes Female Oligopeptides Signal Transduction |
| Zdroj: | International Journal of Peptide and Protein Research. 45:194-199 |
| ISSN: | 0367-8377 |
| DOI: | 10.1111/j.1399-3011.1995.tb01040.x |
| Popis: | Guanosine triphosphatase activating protein (GAP) is an important modulator of p21ras (Ras)-dependent signal transduction in mammalian cells and in insulin-induced maturation of Xenopus oocytes. A synthetic octapeptide from the catalytic domain of GAP, residues 899-906 (F899VFLRLIC906), inhibited GAP-stimulated hydrolysis of GTP to GDP by Ras in an in vitro biochemical assay (IC50= 12 μM). The peptide was assayed for its ability to block insulin- (Ras-dependent) and progesterone- (Ras-independent) induced maturation of stage VI Xenopus laevis oocytes, marked by germinal vesicle breakdown (GVBD). Microinjection of 50 pmol of the peptide inhibited insulin- but not progesterone-induced GVBD by 50%. A 7-residue peptide lacking F899, GAP(900-906)-NH2, failed to inhibit GAP-stimulated GTPase activity and did not block GVBD. Replacement of the cysteine residue at position 906 with methionine resulted in a peptide with prolonged inhibitory activity in the oocyte. Moreover, sequential replacement of specific L-amino acid residues with the corresponding d-mino acids produced a peptide with a two-fold increased half-life after injection into oocytes. None of the peptides tested affected progesterone induced GVBD, suggesting that the modifications did not result in loss of specificity. These studies show that (a) peptides that were able to inhibit GAP-stimulated Ras GTPase activity in vitro were also able to block Ras-dependent GVBD in oocytes, and (b) specific substitutions in these peptides can result in improved stability in oocytes. © Munksgaard 1995. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|