INSULIN STIMULATION OF HIGH-FREQUENCY PHOSPHORYLATION DYNAMICS IN MURINE ERYTHROLEUKEMIA-CELLS

The phosphorylation potentials of two proteins (M(r) 81 kDa and 63 kDa ) in extracts of murine erythroleukemic (MEL) cells both vary in an os cillatory manner, sometimes changing by as much as 100-fold in 10 min. Direct analysis of the temporal changes indicates the existence of pe riodic modulation of the frequencies. amplitudes and mean levels of th e two rhythms. In both cases, periodogram analyses, by two methods, co nfirm the presence of several oscillations having periods in the range 20-100 min which tend to occur in (pseudo) periodic bursts. Insulin h as been found to enhance these oscillations in a manner comparable wit h its effect on rhythmic variations in cell morphology. Despite the ma rked similarity in the behaviour of the two proteins, no particular ph ase relationship existed between the two temporal variations. suggesti ng differences between the underlying driving forces.