Protein phosphatase-1 and -2a activities in cultured fetal chick neurons: differential regulation by insulin and insulin-like growth factor-I

摘要: In this study, we examined the developmental expression and regulation by insulin insulin-like growth factor-I (IGF-I) of protein phosphatase-1 (PP-1) phosphatase-2A (PP-2A) in cultured fetal chick neurons. Protein phosphatase activities were measured using 32P-labeled phosphorylase-a or S6 kinase substrate peptide. cell extracts from day 1-5 cultures, 40-45% spontaneous activity was due to PP-1. PP-2A accounted for remaining 55-60% enzyme activity. Spontaneous PP-1 increased 100% 2 cultures remained constant thereafter. 48% with minimal increases later cultures. Under assay conditions employed, at all times culture a significant proportion (45-50%) an inactive form that could be reactivated trypsin. not influenced Insulin stimulated neuronal 4 5 but had no effect i...