Analysis of protein phosphorylation in fertilized eggs of Rana dybowskii

Abstract

The phosphorylation of 100 and 170 kDa proteins was increased in response to fertilization in eggs of Rana dybowskii. There was a transient increase of inositol 1,4,5-trisphosphate and diacylglycerol in fertilized eggs. Treatment of 0.2 mM CaCl₂ in unfertilized egg homogenate also phosphorylated the 100 and 170 kDa proteins. Data suggest that the sperm signal increases IP₃ content in egg cytoplasm, triggering Ca²⁺ release from internal storage into cell matrix to activate Ca²⁺-dependent protein kinases, necessary for the early embryonic development.