Stimulation of protein phosphorylation during fertilization-induced maturation of Urechis caupo oocytes |
| |
Authors: | L Meijer M Paul D Epel |
| |
Institution: | Hopkins Marine Station, Stanford University, Department of Biological Sciences, Pacific Grove, California 93950 USA |
| |
Abstract: | Protein phosphorylation was studied during fertilization of Urechis caupo oocytes both in vivo, by measuring 32P]phosphate incorporation into 32P preloaded oocytes and in vitro, by measuring endogenous protein kinase and phosphatase activities in homogenates. During fertilization (and maturation) the rate of protein phosphorylation is dramatically increased. No change in the 32P]phosphate uptake, or the nucleotide levels was observed at fertilization, so the increase cannot be attributed to changes in substrate availability. In vitro enzyme assays showed changes in protein kinase activity which approximately mirrored the changes in the in vivo phosphorylation pattern. As there were no changes in protein phosphatase activity, these results suggest the phosphorylation change results from an increase in protein kinase activity. The pattern of change, investigated by SDS-polyacrylamide gel electrophoresis, shows that proteins that were phosphorylated in the unfertilized egg become phosphorylated to a greater degree after fertilization. One protein (48 kd) undergoes an increase followed by a decrease of its phosphorylation level. |
| |
Keywords: | To whom all correspondence should be addressed |
本文献已被 ScienceDirect 等数据库收录! |
|