The association of cell cycle and growth related protein kinases with the fibroblast cytoskeleton /

Abstract

In order for cells to divide, they pass through a regular sequence of growth and division phases, referred to as the cell cycle. These processes are under careful control of the cell's regulatory machinery. It is evident that some protein kinases are the master controllers of these events, since they regulate the activities of multiple proteins. This regulation involves phosphorylating the proteins at specific regulatory sites, activating some, and inhibiting others to coordinate their activities. The regulatory subunits are called cyclins and the catalytic subunits are called cyclin-dependent kinases (cdks). Each cdk catalytic subunit can associate with different cyclins, and the associated cyclin determines which proteins are phosphorylated by the cdk-cyclin complex. To determine the significance of kinases, two kinases (erk and cdc2) were studied in the rat muscle fibroblast. Detergent extractions of fibroblasts yielded an insoluble cytoskeleton fraction containing both erk and cdc2 kinases. Since these kinases are also found in sea urchin blastomere cells, the present study was undertaken to investigate the possibility that erk and cdc2 may help regulate the cell cycle in fibroblast cells. For this reason, this study was established to determine whether a link existed between a somatic cell, and studies previously performed on the sea urchin blastomere.