In vivo prenylation of rat proteins: Modification of proteins with penta- and hexaprenyl groups

In vivo protein prenylation was studied in newborn rats by repeated injecti ons of [H-3]mevalonate. The highest level of protein-bound mevalonate metab olites was found in the kidney, but incorporation was observed in all organ s studied. After fluorography of SDS-polyacrylamide gel electrophoresis-sep arated polypeptides, labeling was found in the 21- to 28-kDa molecular mass region and, after prolonged exposure of the him, additional bands at both higher and lower molecular masses could be detected. Protein prenylation in the kidney increased during the first 5 days after birth, whereas that in the liver reached a maximum on the fourth day. After methyliodide treatment of the prenylated proteins, farnesol, geranylgeraniol, and two larger isop renoids, pentaprenol. and hexaprenol, were released. In the liver, the rati o of protein-bound geranylgeraniol to farnesol increased from 2 to 4.5 duri ng the first 5 days after birth. Upon subfractionation of the kidney, the h ighest level of labeling was found in mitochondria and microsomes. When the mitochondria were subfractionated into outer membranes, intermembrane spac e and an inner membrane/matrix fraction, the labeling pattern of prenylated polypeptides differed in all fractions. The results demonstrate that in vi vo labeling of rats can be performed to study the extent, type, and distrib ution of protein prenylation, (C) 1999 Academic Press.