GTP-dependent conformational changes associated with the functional switch between Galpha and cross-linking activities in brain-derived tissue transglutaminase.
GTP and Ca2+, two well-known modulators of intracellular signaling pathways, control a structural/functional switch between two vital and mutually exclusive activities, cross-linking and Galpha activity, in the same enzyme. The enzyme, a brain-derived tissue-type transglutaminase (TGase), was recently cloned by us in two forms, one of which (s-TGN) lacks a C-terminal region that is present in the other (l-TGN). Immunoreaction with antibodies directed against a peptide present in the C-terminus of l-TGN but missing in s-TGN suggested that this site, which is located in the C-terminal fourth domain, undergoes conformational changes as a result of interaction between l-TGN and GTP. Site-directed mutagenesis suggested that the third domain is involved in mediating the inhibition of the cross-linking activity. These results were supported by molecular modeling, which further suggested that domains III and IV both participate in conformational changes leading to the functional switch between the Ca2+-dependent cross-linking activity and the Galpha activity.
Monsonego
A
A
Department of Neurobiology, The Weizmann Institute of Science, Rehovot, 76100, Israel.
Friedmann
I
I
Shani
Y
Y
Eisenstein
M
M
Schwartz
M
M
D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D001921:Brain / Q000166:cytology / Q000201:enzymology*; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D002460:Cell Line; D003432:Cross-Linking Reagents / Q000737:chemistry / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011233:Precipitin Tests; D011485:Protein Binding / Q000187:drug effects; D011487:Protein Conformation / Q000187:drug effects; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D051381:Rats; D013329:Structure-Activity Relationship; D014162:Transfection; D011503:Transglutaminases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D003432:Cross-Linking Reagents; D006160:Guanosine Triphosphate; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D002118:Calcium