A hemopoietic specific gene encoding a small GTP binding protein is overexpressed during T cell activation.
We have isolated, from a human B cell line cDNA library, a cDNA (Gx) encoding a small G protein identical to rac 2, a member of the ras superfamily. Gx/rac 2 gene is expressed as a unique mRNA of 1,7 Kb in peripheral blood lymphocytes, in purified B and T cells, in thymus as well as in several B and T cell lines. It is not expressed in many other tissues analysed including liver, brain, lung, heart and kidney. Upon in vitro stimulation with phytohemagglutinin A, peripheral blood lymphocytes show a clear increase of the Gx/rac 2 mRNA after 6 hours; a 30-50 fold accumulation is reached at 24 hours and persists thereafter. Purified T lymphocytes exhibit a similar increase in Gx/rac 2 mRNA expression upon mitogenic stimulation. Therefore, the expression of the Gx/rac 2 gene appears to be restricted to cells of the hemopoietic lineage and to be strongly stimulated during T cell activation. Gx/rac 2 protein must fulfill a specific role in activated T cells that could provide a new model for studying the function of small G proteins.
Reibel
L
L
Institut Cochin de Génétique Moléculaire, INSERM U. 257, Paris, France.
Dorseuil
O
O
Stancou
R
R
Bertoglio
J
J
Gacon
G
G
D000595:Amino Acid Sequence; D001402:B-Lymphocytes / Q000502:physiology; D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D020558:GTP Phosphohydrolases / Q000235:genetics*; D019204:GTP-Binding Proteins / Q000235:genetics*; D015870:Gene Expression; D006410:Hematopoiesis; D006801:Humans; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D005810:Multigene Family; D012333:RNA, Messenger / Q000235:genetics; D013601:T-Lymphocytes / Q000502:physiology*; D020744:rac GTP-Binding Proteins
D012333:RNA, Messenger; D004247:DNA; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D020744:rac GTP-Binding Proteins