title: Identification of two allelic forms of ovine CD4 exhibiting a Ser183/Pro183 polymorphism in the coding sequence of domain 3.
abstract: The ovine CD4 cDNA sequence from four sheep sources (Australian Merino, Indonesian Thin Tail, Canadian cross bred, Prealpes du sud) predicts a protein of 455 residues with position 130 in the V2 domain exhibiting a W instead of C suggesting that, like the white whale, dog and cat sequences, sheep CD4 contains only two disulphide bonds. The sequence shows 73% amino acid identity and 83% nucleotide identity to a CD4 sequence from the white whale and significant identity to a partial sequence (314 residues) of bovine CD4 (87% amino acid identity, 93% nucleotide identity). Phylogenetic analysis showed that the ovine CD4 sequence forms a clade with the pig, white whale, dolphin, dog and cat CD4. Two forms of ovine CD4 were identified which differ by a single base pair (T/C) in their cDNA sequence at position 622. This polymorphism is also present in sheep genomic DNA in Hardy-Weinberg equilibrium, suggesting that at least two alleles of CD4 exist in the ovine genome with no selection for a particular allele. This polymorphism changes the first codon position of amino acid 183 and results in a Pro/Ser substitution in the N-terminal region of domain 3 of the CD4 protein.
authors.affiliation: Institute of Parasitology, McGill University, 21111 Lakeshore Road, Ste-Anne-de-Bellevue, Qué. H9X3V9, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Boscariol
authors.forename: J
authors.initials: J
authors.lastname: Pleasance
authors.forename: D M
authors.initials: DM
authors.lastname: Piedrafita
authors.forename: H W
authors.initials: HW
authors.lastname: Raadsma
authors.forename: T W
authors.initials: TW
authors.lastname: Spithill
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015704:CD4 Antigens / Q000235:genetics* / Q000276:immunology; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D020641:Polymorphism, Single Nucleotide; D020033:Protein Isoforms; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D016415:Sequence Alignment; D012756:Sheep / Q000235:genetics* / Q000276:immunology*
chemical_list: D015704:CD4 Antigens; D018076:DNA, Complementary; D020033:Protein Isoforms