A new member of alpha 1-adrenoceptor-coupled G alpha h (transglutaminase II) family in pig heart: purification and characterization.
- Author:
Soon Moon YOO
1
;
Hyun Sik JEONG
;
Kee Jung HAN
;
Sung Hye CHO
;
Hee Sung LEE
;
Hye Young YUN
;
Nyoun Soo KWON
;
Kwang Jin BAEK
Author Information
1. Department of Biochemistry, College of Medicine, Chung-Ang University, Seoul, Korea.
- Publication Type:Original Article ; Research Support, Non-U.S. Gov't
- Keywords:
alpha1-adrenoceptor;
G-protein;
G alpha h transglutaminase;
heart
- MeSH:
Animal;
Binding Sites;
Binding, Competitive;
Cross Reactions;
GTP-Binding Proteins/metabolism*;
GTP-Binding Proteins/isolation & purification*;
GTP-Binding Proteins/immunology;
Guanosine 5'-O-(3-Thiotriphosphate)/metabolism;
Molecular Weight;
Myocardium/chemistry*;
Protein-Glutamine gamma-Glutamyltransferase/metabolism;
Receptors, Adrenergic, alpha-1/metabolism;
Swine
- From:Experimental & Molecular Medicine
1998;30(2):81-86
- CountryRepublic of Korea
- Language:English
-
Abstract:
We previously reported an identification of a 77-kDa GTP-binding protein that co-purified with the alpha 1-adrenoceptor following ternary complex formation. In the present paper, we report on the purification and characterization of this GTP-binding protein (termed G alpha h5) isolated from pig heart membranes. After solubilization of pig heart membranes with NaCl, G alpha h5 was purified by sequential chromatographies using DEAE-Cellulose, Q-Sepharose, and GTP-agarose columns. The protein displayed high-affinity GTP gamma S binding which is Mg(2+)-dependent and saturable. The relative order of affinity of nucleotide binding by G alpha h5 was GTP > GDP > ITP >> ATP > or = adenyl-5'-yl imidodiphosphate, which was similar to that observed for other heterotrimeric G-proteins involved in receptor signaling. Moreover, the G alpha h5 demonstrated transglutaminase (TGase) activity that was blocked either by EGTA or GTP gamma S. In support of these observations, the G alpha h5 was recognized by a specific antibody to G alpha h7 or TGase II, indicating a homology with G alpha h (TGase II) family. These results demonstrate that 77-kDa G alpha h5 from pig heart is an alpha 1-adrenoceptor-coupled G alpha h (TGase II) family which has species-specificity in molecular mass.
