Enhanced prenyltransferase activity and rab content in rat liver regeneration

Rabs are small GTP-binding proteins with a regulatory role in intracellular vesicular traffic. The modulation of their levels and activity in differen t physiological situations is poorly understood. During the first cell cycl e of rat liver regeneration we observed a differential regulation of some R abs, with a progressive increase of those involved in exocytosis and a prog ressive decrease of one involved in endocytosis. This could be related with the need of exposing growth factor receptors and prolonging the transducti on of their signal in preparation for mitosis. Moreover, we observed an inc reased activity of protein prenyltransferases, the enzymes responsible for the prenylation of several proteins involved in crucial processes of prolif eration, without a corresponding increase in the amount of prenyltransferas e protein. (C) 2000 Academic Press.