Insulin and progesterone activate a common synthetic ribosomal protein S6 peptide kinase in Xenopus oocytes.
A synthetic peptide Arg-Arg-Leu-Ser-Ser-Leu-Arg-Ala, the structure of which is based on that of a phosphorylated sequence in ribosomal protein S6, was employed as a probe for stimulated kinase activity in Xenopus laevis oocytes induced to mature with insulin or progesterone. Insulin elicited an early (20-30 min) 3-fold stimulation of S6 peptide phosphorylating activity that was not evident with progesterone. However, both hormones produced a delayed 7-12-fold stimulation of S6 peptide phosphorylating activity at the time of germinal vesicle breakdown. The results of DEAE-Sephacel, Sephacryl S-200, TSK-400, and heparin-Sepharose chromatographic fractionation experiments imply that a common S6 peptide kinase is activated as a consequence of short and long term insulin exposure, as well as in long term progesterone treatment of oocytes. Omission of potassium from the oocyte culture medium greatly facilitated insulin-induced meiotic maturation.
Cicirelli
M F
MF
Howard Hughes Medical Institute, University of Washington, Seattle 98195.
Pelech
S L
SL
Krebs
E G
EG
D000818:Animals; D004789:Enzyme Activation; D005260:Female; D007328:Insulin / Q000494:pharmacology*; D009865:Oocytes / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D010766:Phosphorylation; D011188:Potassium / Q000494:pharmacology; D011374:Progesterone / Q000494:pharmacology*; D011494:Protein Kinases / Q000378:metabolism*; D019893:Ribosomal Protein S6 Kinases; D014982:Xenopus laevis
D007328:Insulin; D011374:Progesterone; D011494:Protein Kinases; D019893:Ribosomal Protein S6 Kinases; D011188:Potassium