Interaction Site of GTP Binding Gh (Transglutaminase II) with Phospholipase C ()

• Published in: The Journal of biological chemistry 1995-11, Vol.270 (45), p.27058-27062
• Main Authors: Hwang, Ki-Chul, Gray, Caroline D., Sivasubramanian, Natarajan, Im, Mie-Jae
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Base Sequence; Binding Sites - genetics; DNA Primers - genetics; DNA, Complementary - genetics; Guanosine Triphosphate - metabolism; Humans; In Vitro Techniques; Molecular Sequence Data; Myocardium - enzymology; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Sequence Deletion; Signal Transduction; Transglutaminases - genetics; Transglutaminases - metabolism; Type C Phospholipases - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.270.45.27058

The GTP binding Gαh (transglutaminase II) mediates the α1B-adrenoreceptor signal to a 69-kDa phospholipase C (PLC). Thus, Gαh 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 Gαh (hhGαh) has been identified that interacts with and stimulates PLC. Expressed mutants of hhGαh with deleted C-terminal regions lost the response to(-)-epinephrine and GTP and failed to coimmunoprecipitate PLC by the specific Gh7α antibody. The interaction regions were further defined by studies with synthetic peptides of hhGαh and a chimera in which residues Val665-Lys672 of hhGαh were substituted with Ile707-Ser714 residues of human coagulation factor XIIIa. Thus, eight amino acid residues near the C terminus of hhGαh are critical for recognition and stimulation of PLC.