title: Covalent modification of G-proteins by affinity labeling.
abstract: The activation of heterotrimeric G-proteins is tightly regulated by the exchange of GTP for GDP in the alpha-subunit; mostly--but not exclusively--seven-transmembrane receptors function as the guanine nucleotide exchange factors (GEFs). A research goal may be to determine which G-protein alpha-subunit is activated by the receptor under investigation. In a membrane preparation obtained from cells or tissues this can be achieved in a seemingly straightforward manner by determining if the receptor increases the covalent incorporation of GTP analogs into G-protein alpha-subunits. Because the GTP analogs may be labeled to high specific radioactivity the alpha-subunit can then be identified with the use of specific antibodies. One of the compounds we present here (2',3'-dialdehyde-GTP) can also be employed to block receptor-mediated G-protein activation and to disrupt the cognate signaling pathway.
authors.affiliation: Institute of Pharmacology, Vienna University, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Hohenegger
authors.forename: Michael
authors.initials: M
authors.lastname: Freissmuth
authors.forename: Christian
authors.initials: C
authors.lastname: Nanoff
mesh_terms: D000345:Affinity Labels / Q000378:metabolism*; D000818:Animals; D001386:Azides / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism; D006801:Humans; D010084:Oxidation-Reduction; D010761:Phosphorus Radioisotopes / Q000378:metabolism
chemical_list: D000345:Affinity Labels; D001386:Azides; D010761:Phosphorus Radioisotopes; C031907:GTP gamma-4-azidoanilide; D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins