Interaction site of GTP binding Gh (transglutaminase II) with phospholipase C.
The GTP binding G alpha h (transglutaminase II) mediates the alpha 1B-adrenoreceptor signal to a 69-kDa phospholipase C (PLC). Thus, G alpha h possesses both GTPase and transglutaminase activities with a signal transfer role. The recognition sites of this unique GTP binding protein for either the receptor or the effector are completely unknown. A site on human heart G alpha h (hhG alpha h) has been identified that interacts with and stimulates PLC. Expressed mutants of hhG alpha h with deleted C-terminal regions lost the response to (-)-epinephrine and GTP and failed to coimmunoprecipitate PLC by the specific Gh7 alpha antibody. The interaction regions were further defined by studies with synthetic peptides of hhG alpha h and a chimera in which residues Val665-Lys672 of hhG alpha h were substituted with Ile707-Ser714 residues of human coagulation factor XIIIa. Thus, eight amino acid residues near the C terminus of hhG alpha h are critical for recognition and stimulation of PLC.
Hwang
K C
KC
Department of Molecular Cardiology, Research Institute, Cleveland Clinic Foundation, Ohio 44195, USA.
Gray
C D
CD
Sivasubramanian
N
N
Im
M J
MJ
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009206:Myocardium / Q000201:enzymology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D015398:Signal Transduction; D011503:Transglutaminases / Q000235:genetics / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism*
D017931:DNA Primers; D018076:DNA, Complementary; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D006160:Guanosine Triphosphate; D011503:Transglutaminases; D010738:Type C Phospholipases