Small G proteins are expressed ubiquitously in lymphoid cells and do not correspond to Bcl-2

In a large percentage of B-cell lymphomas, tumors of the lymphatic system, a translocation (in which certain regions of chromosomes are moved to another chromosome) occurs between chromosome 14 and 18, which moves a portion of the oncogene (tumor-causing gene) Bcl-2. Because of the change in chromosomal region, the Bcl-2 gene is no longer regulated and the protein the gene encodes, Bcl-2, is produced in large amounts. The Bcl-2 protein has been shown to have a function in the survival of cells, in the enhancement of the growth of cells, and in uncontrolled growth, i.e. cancer. It was thought that Bcl-2 binds guanidine triphosphate nucleotide (GTP) and this binding is thought to mediate the biological effects of Bcl-2. The levels of GTP binding proteins (G proteins) were examined in lymphoid cells that expressed Bcl-2. Several small G proteins, which were the same size as Bcl-2, were found to be expressed, but the level of expression did not change in cancerous cells, as does Bcl-2. Using protein chemistry and cell biological techniques, the Bcl-2 protein was separated from the small G proteins. It was shown that Bcl-2 did not bind GTP directly. Thus, the biochemical role of Bcl-2 is not known and the mechanisms behind its role in uncontrolled growth remain unknown as well. (Consumer Summary produced by Reliance Medical Information, Inc.)