title: Cloning of a urochordate cDNA featuring mammalian short consensus repeats (SCR) of complement-control protein superfamily.
abstract: Mammalian tumor necrosis factor (TNF)-alpha degenerate polymerase chain reaction (PCR) primers were used to amplify a probe from Botryllus schlosseri (colonial ascidian) allogeneic rejection-cDNA library. A PCR product (269 bp) was cloned and sequenced encoding an open reading frame (ORF) of 89 amino acids (aa). This clone, which revealed no similarity to TNF-alpha, but a substantial similarity to mammalian proteins featuring short consensus repeats (SCRs) of the complement control superfamily, was used to probe the rejection-cDNA library. Two partial cDNA clones were isolated and sequenced (Bs.1, 846 bp; Bs.2, 712 bp). The longest ORF in clone Bs.1 (which lacks the 5' end of the cDNA) predicts a protein of 251 aa, which differs from Bs.2 at six nucleotides and four aa. We compare the aa similarity (up to 50.5%) of Bs.1 with the SCR-region of mammalian complement factor H, apolipoprotein H, selectins, and complement receptors type 1 and type 2. A somatomedin B-like domain at the C-terminus of Bs.1 deduced protein was also recorded. We propose that this mosaic and polymorphic botryllid sequence, featuring mammalian-like SCRs, might be an ancestral molecule in the evolution of the chordate's complement-control protein superfamily.
authors.affiliation: Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa, Israel.
authors.forename: Z
authors.initials: Z
authors.lastname: Pancer
authors.forename: H
authors.initials: H
authors.lastname: Gershon
authors.forename: B
authors.initials: B
authors.lastname: Rinkevich
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D017124:Conserved Sequence; D017931:DNA Primers; D018076:DNA, Complementary; D016208:Databases, Factual; D006801:Humans; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011257:Pregnancy Proteins / Q000737:chemistry / Q000235:genetics; D011506:Proteins / Q000737:chemistry* / Q000235:genetics*; D011817:Rabbits; D012091:Repetitive Sequences, Nucleic Acid; D017386:Sequence Homology, Amino Acid; D014409:Tumor Necrosis Factor-alpha / Q000737:chemistry / Q000235:genetics; D014561:Urochordata / Q000737:chemistry* / Q000235:genetics*; D019096:Vitronectin / Q000737:chemistry / Q000235:genetics
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D008562:Membrane Glycoproteins; D011257:Pregnancy Proteins; D011506:Proteins; D014409:Tumor Necrosis Factor-alpha; D019096:Vitronectin