Cellular distribution of cholesterogenesis‐linked, phosphoisoprenylated proteins in proliferating cells

Abstract

A set of isoprenylated proteins has been detected in rapidly proliferating, suspension-grown murine lymphoma cells. Our evidence indicates that all of these isoprenylated proteins are phosphorylated. Subsequent to a 24 h incubation with mevinolin to deplete the intracellular mevalonate (MVA) level, cells were incubated with PHIMVA and/or 3ZPi and both total cell and subcellular fraction proteins were resolved via 1-and 2-D gel electrophoresis, then assessed via subsequent autoradiography. The phospho-isoprenylated proteins comprise a set spanning a molecular mass range of 21-69 kDa and all dispay acidic PI. MVA-derivatized proteins of 21-24 kDa, which consist of multiple isoforms, are present in both cytosolic and nuclear fractions. Larger phospho-isoprenylated protein species (4469 kDa) are specifically localized within the nucleus, where applicable extraction protocols indicate that they are part of or closely affiliated with the nuclear matrix-intermediate filament (NM-IF) components. The localization of the 69 kDa prenylated species within the NM-IF fraction, together with evidence of its phosphorylation, supports recent indications that this protein is the nuclear matrix component lamin B.

Lipopolysaccharide-induced NF-kappa B activation in mouse 70Z/3 pre-B lymphocytes is inhibited by mevinolin and 5'-methylthioadenosine: roles of protein isoprenylation and carboxyl methylation reactions.

“…2 to 4). These results are consistent with those previously obtained with these cells in the similar experiments of Sepp-Lorenzino et al (43). Furthermore, the latter authors showed that very few of the isoprenylated proteins were present in the microsomal membrane fraction, where we detect protein methylation.…”

“…5). These results are similar to those previously obtained by Sepp-Lorenzino et al (43). The patterns of isoprenylated proteins from either MTA-or LPS-treated 70Z/3 cells were qualitatively and quantitatively similar compared with those of untreated cultures after normalization to Coomassie-stained protein bands ( Fig.…”

“…that many of the methylated species may not in fact be isoprenylated as well. This result is also in accord with the paucity of isoprenylated proteins that Sepp-Lorenzino et al (43) detected in the membrane fraction. However, the inherent difficulty in labeling mevalonate-derivatized proteins to high specific activity necessitated much longer incubation times than were required to detect protein carboxyl methylation.…”

“…Inhibition of mevalonate biosynthesis in turn blocks the isoprenylation of ras proteins and prevents their membrane association and transforming activity (17). It has already been shown that protein isoprenylation occurs in a number of nuclear and cytoplasmic proteins in 70Z/3 cells (43). Furthermore, evidence has been presented that the LPS response is associated with the activation of a heterotrimeric large G protein in mouse B-lymphocyte and macrophage cell lines (20) and in a human promonocytic cell line (6).…”

Protein Farnesyltransferase and Protein Prenylation inPlasmodium falciparum

“…Earlier studies reported cell-cycle or differentiation dependent protein prenylation in synchronized HepG2 cells (57) and in the seminiferous epithelium of rats at different stages of spermatogenesis (40). The studies in HepG2 cells led the authors to suggest that protein prenylation could constitute an obligatory step leading to the duplication of the cellular genome.…”