Periodic synthesis of microtubular proteins in the cell cycle of Physarum.

Abstract

Periodic polypeptide labeling over the naturally synchronous nuclear replication cycle of P. polycephalum was analyzed by fluorography of 2-dimensional electropherograms. Two sets of polypeptides, denoted as P and Q, showed strong periodicity; they were maximally labeled just prior to mitosis. This periodicity was shown to reflect synthesis rather than turnover or recovery. Both P and Q copolymerized with porcine microtubular proteins and displayed electrophoretic properties similar to those of porcine tubulins. The significance of the periodic synthesis of these microtubular proteins is discussed as a possible component within the chain of events that establishes the high mitotic synchrony of Physarum syncytia.