Small G proteins are expressed ubiquitously in lymphoid cells and do not correspond to Bcl-2.
The bcl-2 gene is consistently associated with t(14; 18) chromosomal translocations observed in a large fraction of human B-cell lymphomas. The t(14; 18) translocation results in deregulated expression of the bcl-2 gene and synthesis of inappropriately high levels of the Bcl-2 protein. Gene transfer studies suggest a role for Bcl-2 in cell survival, growth enhancement and oncogenic transformation. To test the suggestion that GTP-binding by Bcl-2 may mediate its biological effects we characterized the GTP-binding proteins in lymphoid cells expressing Bcl-2. Expression of several small GTP-binding proteins was found to be ubiquitous and did not vary with levels of Bcl-2. By using immunological, electrophoretic and cell-fractionation techniques, we separated Bcl-2 from G proteins of small relative molecular mass (Mr) and showed that it is incapable of binding GTP. Our results show that small Mr G proteins are widely expressed in lymphoid cells and that Bcl-2 is not a novel member of this GTP-binding protein family.
Monica
K
K
Department of Pathology, Stanford University Medical Center, California 94305.
Chen-Levy
Z
Z
Cleary
M L
ML
D000818:Animals; D015153:Blotting, Western; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006801:Humans; D008214:Lymphocytes / Q000502:physiology*; D051379:Mice; D008970:Molecular Weight; D011233:Precipitin Tests; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2; D013347:Subcellular Fractions / Q000378:metabolism; D014407:Tumor Cells, Cultured
D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins