Changes in phosphorylation of an F-actin capping protein of Physarum polycephalum during the cell cycle.
The Cap 42(b), a Ca2+-dependent F-actin capping phosphoprotein of 42,000 daltons, was shown to be localized in the cytosol of Physarum polycephalum by measurements of phosphorylatability in the absence of Ca2+. The phosphorylation of Cap 42(b) in the cytosol changed during the cell cycle: it was high in the S and G2 phase, and low in the M phase and boundary phase between S and G2 phase. When the isolated Cap 42(b) was added to M phase cytosol, the phosphorylation of Cap 42(b) was significantly increased by at least 6-fold. Compared with this result, about 2-fold increase in the phosphorylation of Cap 42(b) was observed when the Cap 42(b) kinase was added to M phase cytosol. Therefore, it is likely that the low level of Cap 42(b) phosphorylation in M phase cytosol is mostly due to the decreased amount of phosphorylatable Cap 42(b) and to a lesser extent due to a low level of the Cap 42(b) kinase activity.
D000199:Actins / Q000378:metabolism*; D002118:Calcium / Q000502:physiology; D002453:Cell Cycle; D003600:Cytosol / Q000378:metabolism; D007399:Interphase; D008840:Microfilament Proteins / Q000378:metabolism*; D008938:Mitosis; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D010804:Physarum / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D011494:Protein Kinases / Q000378:metabolism
D000199:Actins; D008840:Microfilament Proteins; D010750:Phosphoproteins; D011494:Protein Kinases; D002118:Calcium