Metaphase protein phosphorylation in Xenopus laevis eggs.

摘要: Cytoplasmic extracts of metaphase (M-phase)-arrested Xenopus laevis eggs support nuclear envelope breakdown and chromosome condensation in vitro. Induction is inhibited by AMPP(NH)P, a nonhydrolyzable ATP analog, but not or gamma-S-ATP, hydrolyzable suggesting that protein phosphorylation may be required for M-phase events By addition [gamma-32P]ATP, we have identified cytoplasmic intact at least six phosphoproteins are present during absent G1/S-phase. These also appear response to partially purified preparations maturation-promoting factor. A subset these proteins thiophosphorylated gamma-S-ATP under conditions promote condensation. Each phosphorylated on serine threonine, one, 42-kilodalton protein, tyrosine both eggs. results indicate activation kinases accounts part the increased protein-serine-threonine protein-tyrosine play role controlling behavior.