title: Specific interactions between gC1qR and alpha1-adrenoceptor subtypes.
abstract: The multi-functional protein gC1qR has been reported to interact with an arginine-rich motif in the C-tail of hamster alpha1B-adrenoceptors (ARs), controlling their expression and subcellular localization. Since a similar motif is present in alpha1D-, but not alpha1A-ARs, we studied the specificity of this interaction. Human alpha1-ARs, tagged at their amino termini with Flag epitopes, were coexpressed in HEK293 cells with gC1qR containing a hemaglutinin (HA) tag at its carboxy terminus. Immunoprecipitation studies showed that Flag-alpha1B- or alpha1D-, but not alpha1A-ARs, caused coimmunoprecipitation of HA-gC1qR, while immunoprecipitation of HA-gC1qR caused coimmunoprecipitation of Flag-alpha1B- or alpha1D-, but not alpha1A-ARs, supporting specific interactions between subtypes. C-terminal truncation of Flag-alpha1-ARs prevented interaction with HA-gC1qR, supporting previous conclusions about the role of the C-terminal arginine-rich motif. These studies suggest that gC1qR interacts specifically with alpha1B- and alpha1D-, but not alpha1A-ARs, and this interaction depends on the presence of an intact C-tail.
authors: Department of Pharmacology, Rollins Research Center, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
authors: Andre S
authors: AS
authors: Pupo
authors: Kenneth P
authors: KP
authors: Minneman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins; D002460:Cell Line; D006224:Cricetinae; D006801:Humans; D018960:Hyaluronan Receptors; D008562:Membrane Glycoproteins / Q000378:metabolism; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000378:metabolism; D017434:Protein Structure, Tertiary; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000235:genetics / Q000378:metabolism*; D011951:Receptors, Complement / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: C087299:C1QBP protein, human; C490195:C1qbp protein, rat; D002352:Carrier Proteins; D018960:Hyaluronan Receptors; D008562:Membrane Glycoproteins; D024101:Mitochondrial Proteins; D020033:Protein Isoforms; D018340:Receptors, Adrenergic, alpha-1; D011951:Receptors, Complement; D011993:Recombinant Fusion Proteins; C032402:complement 1q receptor