title: In vivo effects of microinjected alkaline phosphatase and its low molecular weight substrates on the first meiotic cell division in Xenopus laevis oocytes.
abstract: Xenopus laevis oocytes were microinjected with low molecular weight phosphoesters such as 2-glycerophosphate, phosphotyrosine, phosphoserine, phosphothreonine, 4-nitrophenyl phosphate, and orthophosphate. These compounds were able to induce a considerable reduction in the time course of progesterone-induced maturation, with 2-glycerophosphate being the most effective. The basal level of cAMP and its drop during maturation were not affected by the microinjection of 2-glycerophosphate. The injection of alkaline phosphatase (EC 3.1.3.1.) from calf intestine at a low concentration (10 ng per oocyte) was able to decrease or abolish the effect of 2-glycerophosphate. At higher concentration (25 ng per oocyte) this enzyme totally blocked progesterone- or maturation-promoting factor-induced maturation. Alkaline phosphatase might behave in vivo as a phosphoprotein phosphatase active towards phosphotyrosine-containing proteins. In addition, our results indicate that phosphate or phosphoester-containing buffers should be avoided in the course of maturation-promoting factor purification.
mesh_terms: D000469:Alkaline Phosphatase / Q000494:pharmacology*; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D000242:Cyclic AMP / Q000032:analysis; D005260:Female; D007700:Kinetics; D008540:Meiosis / Q000187:drug effects*; D008845:Microinjections; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D010710:Phosphates / Q000494:pharmacology*; D011374:Progesterone / Q000494:pharmacology; D014981:Xenopus
chemical_list: D010710:Phosphates; D011374:Progesterone; D000242:Cyclic AMP; D000469:Alkaline Phosphatase