title: The Oka blood group antigen is a marker for the M6 leukocyte activation antigen, the human homolog of OX-47 antigen, basigin and neurothelin, an immunoglobulin superfamily molecule that is widely expressed in human cells and tissues.
abstract: The high-frequency blood group antigen Ok(a) is carried on a red cell membrane glycoprotein (gp) of 35-69 kDa that is widely distributed on malignant cells of different origins. Immunostaining of hemopoietic cells and a range of normal human tissues demonstrated a wide distribution of the Ok(a) gp that appears to be nonlineage-restricted, although certain tissues show differentiation-related expression. Ok(a) gp was purified from red cell membranes by immunoaffinity chromatography using mAb A103 and amino acid sequence analysis was performed. The N-terminal 30 amino acids are identical to the predicted sequence of M6 leukocyte activation antigen (M6), a member of the Ig superfamily (IgSF) with two IgSF domains. There are homologs in rat (MRC OX-47 or CE9), in mouse (basigin or gp42), and in chicken (HT7 or neurothelin). The molecular basis of the Ok(a) mutation was established by sequencing M6 cDNA derived from normal and Ok(a-) EBV-transformed B cell lines. A point mutation in the translated portion of M6 cDNA, G331AG-->AAG gives rise to a predicted E92-->K amino acid change in the first Ig-like domain of the Ok(a-) form of the protein. Transfection of mouse NS-0 cells with normal or Ok(a-) cDNA confirmed the identity of the protein and only the Ok(a-) transfectants failed to react with monoclonal anti-Ok(a) Ab.
authors.affiliation: Bristol Institute for Transfusion Sciences, GB. fran.spring@msmail.nbs.nhs.uk
authors.forename: F A
authors.initials: FA
authors.lastname: Spring
authors.forename: C H
authors.initials: CH
authors.lastname: Holmes
authors.forename: K L
authors.initials: KL
authors.lastname: Simpson
authors.forename: W J
authors.initials: WJ
authors.lastname: Mawby
authors.forename: M J
authors.initials: MJ
authors.lastname: Mattes
authors.forename: Y
authors.initials: Y
authors.lastname: Okubo
authors.forename: S F
authors.initials: SF
authors.lastname: Parsons
mesh_terms: D000017:ABO Blood-Group System / Q000096:biosynthesis / Q000097:blood* / Q000302:isolation & purification; D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD; D000951:Antigens, Neoplasm; D000954:Antigens, Surface / Q000096:biosynthesis / Q000097:blood* / Q000302:isolation & purification; D030161:Avian Proteins; D051926:Basigin; D015415:Biomarkers / Q000097:blood; D001798:Blood Proteins; D006412:Hematopoietic Stem Cells / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007136:Immunoglobulins / Q000737:chemistry* / Q000235:genetics; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000097:blood* / Q000302:isolation & purification; D051379:Mice; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000276:immunology; D051381:Rats
chemical_list: D000017:ABO Blood-Group System; D015703:Antigens, CD; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D030161:Avian Proteins; C497886:BSG protein, human; D015415:Biomarkers; D001798:Blood Proteins; C102624:Bsg protein, Gallus gallus; C497887:Bsg protein, mouse; C079432:Bsg protein, rat; D007136:Immunoglobulins; D008562:Membrane Glycoproteins; D051926:Basigin