HIGH-FREQUENCY OSCILLATIONS IN THE ACTIVITY OF PHOSPHOTYROSINE PHOSPHATASE IN MURINE ERYTHROLEUKEMIC CELLS - ACTION OF INSULIN AND HEXAMETHYLENE BISACETAMIDE

We have previously reported oscillations in the activities of the phos phoamino acid phosphatases in murine erythroleukaemic cells. In keepin g with our predictions we now show that the phosphotyrosine phosphatas e activity rhythm has a much shorter period than originally seemed the case: being of the order of 10 min and probably less. The periodic ch anges show evidence of rhythmic modulation of mean, period and amplitu de as with all other cellular oscillations studied. Insulin decreases the frequency of the rhythm while the inducer of differentiation, hexa methylene bisacetamide (HMBA) decreases its amplitude. Current ideas o n phosphorylation dynamics in relation to metabolism and mitosis may n eed to be revised in the light of the observations. (C) 1996 Academic Press Limited