Search results for "GTP Phosphohydrolases"
showing 3 items of 23 documents
Ras, Rap, and Rac Small GTP-binding Proteins Are Targets for Clostridium sordellii Lethal Toxin Glucosylation
1996
Lethal toxin (LT) from Clostridium sordellii is one of the high molecular mass clostridial cytotoxins. On cultured cells, it causes a rounding of cell bodies and a disruption of actin stress fibers. We demonstrate that LT is a glucosyltransferase that uses UDP-Glc as a cofactor to covalently modify 21-kDa proteins both in vitro and in vivo. LT glucosylates Ras, Rap, and Rac. In Ras, threonine at position 35 was identified as the target amino acid glucosylated by LT. Other related members of the Ras GTPase superfamily, including RhoA, Cdc42, and Rab6, were not modified by LT. Incubation of serum-starved Swiss 3T3 cells with LT prevents the epidermal growth factor-induced phosphorylation of m…
rhoB encoding a UV-inducible Ras-related small GTP-binding protein is regulated by GTPases of the Rho family and independent of JNK, ERK, and p38 MAP…
1998
The small GTPase RhoB is immediate-early inducible by DNA damaging treatments and thus part of the early response of eukaryotic cells to genotoxic stress. To investigate the regulation of this cellular response, we isolated the gene for rhoB from a mouse genomic library. Sequence analysis of the rhoB gene showed that its coding region does not contain introns. The promoter region of rhoB harbors regulatory elements such as TATA, CAAT, and Sp1 boxes but not consensus sequences for AP-1, Elk-1, or c-Jun/ATF-2. The rhoB promoter was activated by UV irradiation, but not by 12-O-tetradecanoylphorbol-13-acetate treatment. rhoB promoter deletion constructs revealed a fragment of 0.17 kilobases in …
Rho GTPases are over-expressed in human tumors.
1999
Small GTPases of the Rho family are involved in the regulation of a variety of cellular processes, such as the organization of the microfilamental network, cell-cell contact and malignant transformation. To address the question of whether Rho proteins are involved in carcinogenesis in man, we compared their expression in tumors from colon, breast and lung with that of the corresponding normal tissue originating from the same patient. As shown by Rho-specific 32P-ADP-ribosylation, as well as Western-blot analysis, the amount of RhoA protein was largely increased in all 3 types of tumors tested. The most dramatic differences in the expression of Rho GTPases were observed in breast tissue. All…