Gh: a GTP-binding protein with transglutaminase activity and receptor signaling function.
The alpha 1-adrenergic receptors activate a phospholipase C enzyme by coupling to members of the large molecular size (approximately 74 to 80 kilodaltons) G alpha h family of guanosine triphosphate (GTP)-binding proteins. Rat liver G alpha h is now shown to be a tissue transglutaminase type II (TGase II). The transglutaminase activity of rat liver TGase II expressed in COS-1 cells was inhibited by the nonhydrolyzable GTP analog guanosine 5'-O-(3-thiotriphosphate) or by alpha 1-adrenergic receptor activation. Rat liver TGase II also mediated alpha 1-adrenergic receptor stimulation of phospholipase C activity. Thus, G alpha h represents a new class of GTP-binding proteins that participate in receptor signaling and may be a component of a complex regulatory network in which receptor-stimulated GTP binding switches the function of G alpha h from transglutamination to receptor signaling.
Nakaoka
H
H
Department of Cardiovascular Biology, Cleveland Clinic Foundation, OH 44195.
Perez
D M
DM
Baek
K J
KJ
Das
T
T
Husain
A
A
Misono
K
K
Im
M J
MJ
Graham
R M
RM
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D004837:Epinephrine / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006168:Guinea Pigs; D007295:Inositol Phosphates / Q000378:metabolism; D008099:Liver / Q000201:enzymology; D008969:Molecular Sequence Data; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D011942:Receptors, Adrenergic, alpha / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection; D011503:Transglutaminases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism
C527821:Ghalpha protein, rat; D007295:Inositol Phosphates; D011942:Receptors, Adrenergic, alpha; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D011503:Transglutaminases; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D011224:Prazosin; D004837:Epinephrine