These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: ADP-ribosylation of Rho proteins by Clostridium botulinum exoenzyme C3 is influenced by phosphorylation of Rho-associated factors.
    Author: Fritz G, Aktories K.
    Journal: Biochem J; 1994 May 15; 300 ( Pt 1)(Pt 1):133-9. PubMed ID: 8198524.
    Abstract:
    Specific [32P]ADP-ribosylation by Clostridium botulinum exoenzyme C3 was used to study the involvement of phosphorylation in the regulation of the low-molecular-mass GTP-binding protein Rho. Dephosphorylation of CHO cell extracts by alkaline phosphatase treatment resulted in a 80-90% reduction in the C3-catalysed [32P]ADP-ribosylation of Rho proteins in both cytosolic and membrane fractions. Similar results were obtained after dephosphorylation with protein phosphatase type-1 from bovine retina, whereas type-2B and type-2C phosphatases had no effect on the level of subsequent [32P]ADP-ribosylation of Rho by C3. Incubation of CHO cell lysate under phosphorylation conditions increased the subsequent C3-mediated [32P]ADP-ribosylation of Rho proteins. The protein kinase inhibitors H7 and H9 had no effect on [32P]ADP-ribosylation at concentrations which are specific for inhibition of protein kinase A or C. Recombinant glutathione S-transferase-RhoA fusion protein (GST-RhoA) was phosphorylated by protein kinase A; however, the phosphorylation had no stimulatory effect on the ADP-ribosylation of GST-RhoA by C3. An approx. 48 kDa phosphoprotein was identified which bound specifically to recombinant GST-RhoA fusion protein. By gel-permeation chromatography, Rho-containing complexes of approx. 50 kDa and 130-170 kDa were detected. The ADP-ribosylation of Rho in the 130-170 kDa complex was reduced by alkaline phosphatase pretreatment. The data suggest that Rho activity is influenced by phosphorylation of Rho-associated regulatory factors. Phosphorylation/dephosphorylation of these Rho-regulating factors appears to alter the ability of Rho to serve as a substrate for C3-induced [32P]ADP-ribosylation.
    [Abstract] [Full Text] [Related] [New Search]