title: Unique epitopes in RNA helicase II/Gu protein recognized by serum from a watermelon stomach patient.
abstract: RNA helicase II/Gu (RH II/Gu) is a nucleolar antigen originally identified using an autoimmune serum from a patient with watermelon stomach. A later report showed that anti-RH II/Gu autoantibodies were also present at low frequency in connective tissue disease (CTD) patients who did not show any symptoms suggestive of a watermelon stomach lesion. In an attempt to understand the relationship between watermelon stomach, also called gastric antral vascular ectasia (GAVE), and autoimmune disorder, we identified the antigenic sites recognized by these autoantibodies. Serum Gu uniquely recognized epitopes at amino acids 646-748 of RH II/Gu and all four CTD patient sera recognized antigenic sites within amino acids 1-173. Anti-RH II/Gu serum produced by immunizing rabbit with recombinant human RH II/Gu protein bound to the same antigenic sites recognized by the CTD patient sera, but it did not recognize the serum Gu epitopes. Results are also presented showing the use of these anti-RH II/Gu antibodies in the analysis of the evolutionary conservation of RH II/Gu in human, monkey and mouse.
authors.affiliation: Department of Pharmacology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Garcia
authors.forename: J
authors.initials: J
authors.lastname: Zhou
authors.forename: D
authors.initials: D
authors.lastname: Henning
authors.forename: F C
authors.initials: FC
authors.lastname: Arnett
authors.forename: B C
authors.initials: BC
authors.lastname: Valdez
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001323:Autoantibodies / Q000097:blood / Q000276:immunology; D003240:Connective Tissue Diseases / Q000276:immunology; D017124:Conserved Sequence; D018604:Epitope Mapping / Q000379:methods; D018985:Epitopes, B-Lymphocyte / Q000235:genetics / Q000276:immunology*; D020252:Gastric Antral Vascular Ectasia / Q000097:blood / Q000276:immunology*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000276:immunology*; D020365:RNA Helicases / Q000235:genetics / Q000276:immunology*; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology; D020539:Sequence Analysis, Protein / Q000379:methods; D017386:Sequence Homology, Amino Acid
chemical_list: D001323:Autoantibodies; D018985:Epitopes, B-Lymphocyte; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D020365:RNA Helicases