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Expression of a 24 kDa GTP-binding protein (Gn24) is increased in lovastatin treated human erythroleukemia cells.

Expression of a 24 kDa GTP-binding protein (Gn24) is increased in lovastatin treated human erythroleukemia cells.

Authors :
Bhullar RP
Source :
Molecular and cellular biochemistry [Mol Cell Biochem] 1996 Mar 09; Vol. 156 (1), pp. 59-67.
Publication Year :
1996

Abstract

A major 27 kDa particulate and a minor 24 kDa cytosolic GTP-binding protein was detected in HEL cells upon incubation with [alpha-32P]GTP of nitrocellulose blots containing polypeptides separated using SDS-PAGE. Addition of lovastatin (30 microM) to HEL cells in culture inhibited protein synthesis by approximately 35%. However, this treatment resulted in a 5-fold increase, as quantitated by [alpha-32P]GTP binding, in the amount of cytosolic 24 kDa GTP-binding protein. Addition of cycloheximide plus lovastatin to cells in culture abolished the observed increase in 24 kDa GTP-binding protein. Incubation of cells with lovastatin plus [R,S]-[5-(3)H] mevalonolactone resulted in the incorporation of radioactivity into several polypeptides in both the cytosolic and particulate fractions including a polypeptide of molecular mass of 24 kDa in the cytosol. The mobility of this 24 kDa isoprenylated protein on SDS-PAGE was identical to that of the GTP-binding protein increased in response to lovastatin. However, the 24 kDa protein remained in the cytosol after undergoing isoprenylation. The 24 kDa protein was distinct from the HEL cell, G25K/CDC42Hs GTP-binding protein and the GTP-binding protein that was a substrate for botulinum toxin C3 catalyzed ADP-ribosylation. Results demonstrate that lovastatin specifically increases the expression of a 24 kDa GTP-binding protein in HEL cells and that, isoprenylation of low molecular mass GTP-binding protein(s) may have function(s) in addition to its role in the targetting of these proteins to cell membrane.

Details

Language :
English
ISSN :
0300-8177
Volume :
156
Issue :
1
Database :
MEDLINE
Journal :
Molecular and cellular biochemistry
Publication Type :
Academic Journal
Accession number :
8709977
Full Text :
https://doi.org/10.1007/BF00239320