Gem, a GTP-binding protein from mitogen-stimulated T cells, is induced in endothelial cells upon activation by inflammatory cytokines.
Using differential screening of cytokine-activated versus resting porcine aortic endothelial cells (PAEC), we have isolated a member of the family of Ras/GTP-binding proteins. The cDNA encodes a 34-kilodalton protein showing 97% homology to Gem, a gene recently isolated from activated T cells, likely representing its porcine homologue. The amino acid sequence differs from the Ras consensus by the absence of a C-terminal isoprenylation site and a glycine to glutamic acid substitution in the third GTP-binding domain. We report here, that pigGem mRNA is strongly inducible in PAEC upon activation by either IL-1 alpha, TNF alpha or lipopolysaccharide (LPS). Low constitutive expression is found in several organs. Epitope-tagged pigGem transfected into endothelial cells (EC) localizes to the cytoplasm and to the inner side of the plasma membrane. Structural features of Gem and its inducibility apparently restricted to T cells and endothelial cells, together with Rad, a GTPase overexpressed in skeletal muscle cells of type II diabetic individuals, define a new branch within the superfamily of GTP-binding proteins.
Vanhove
B
B
Vienna International Research Cooperation Center (VIRCC), Austria.
Hofer-Warbinek
R
R
Kapetanopoulos
A
A
Hofer
E
E
Bach
F H
FH
de Martin
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D003001:Cloning, Molecular; D016207:Cytokines / Q000494:pharmacology*; D018076:DNA, Complementary / Q000235:genetics; D004730:Endothelium, Vascular / Q000737:chemistry / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000032:analysis / Q000235:genetics*; D018628:Gene Dosage; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D017874:Immediate-Early Proteins / Q000032:analysis / Q000235:genetics*; D007375:Interleukin-1 / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008934:Mitogens / Q000494:pharmacology; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins; D009928:Organ Specificity; D012333:RNA, Messenger / Q000096:biosynthesis; D017386:Sequence Homology, Amino Acid; D013552:Swine; D013601:T-Lymphocytes / Q000737:chemistry*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D016207:Cytokines; D018076:DNA, Complementary; D017874:Immediate-Early Proteins; D007375:Interleukin-1; D008070:Lipopolysaccharides; D008934:Mitogens; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D019204:GTP-Binding Proteins; D020559:Monomeric GTP-Binding Proteins