1. Gh: a GTP-binding protein with transglutaminase activity and receptor signaling function
- Author
-
Nakaoka, Hideaki, Perez, Dianne M., Baek, Kwang Jin, Das, Tanya, Husain, Ahsan, Misono, Kunio, Im, Mie-Jae, and Graham, Robert M.
- Subjects
Transglutaminases -- Physiological aspects ,Enzyme inhibitors -- Physiological aspects ,G proteins -- Physiological aspects ,Science and technology ,Physiological aspects - Abstract
The [alpha.sub.1] adrenergic receptors activate a phospholipase C enzyme by coupling to members of the large molecular size (approximately 74 to 80 kilodaltons) [G[alpha.sub.h] family of guanosine triphosphate (GTP)-binding proteins. Rat liver [G[alpha.sub.h] is now shown to be a tissue transglutaminasetype 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.sub.1]-adrenergic receptor activation. Rat liver TGase II also mediated [alpha.sub.1]-adrenergic receptor stimulation of phospholipase C activity. Thus, [G[alpha.sub.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.sub.h] from transglutamination to receptor signaling., We have shown previously that a GTP-binding protein, termed [G.sub.h] copurifies with rat liver [alpha.sub.1]-adrenergic receptors in a ternary complex containing [alpha.sub.1]-agonist, the receptor, and [G.sub.h][1]. De novo purification of [...]
- Published
- 1994