Cloning of a urochordate cDNA featuring mammalian short consensus repeats (SCR) of complement-control protein superfamily

• Published in: Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology Vol. 111; no. 4; pp. 625 - 632
• Main Authors: Pancer, Z., Gershon, H., Rinkevich, B.
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 01.08.1995
• Subjects: Amino Acid Sequence; Animals; Ascidiacea; Base Sequence; Botryllus schlosseri; Cloning, Molecular; Complement; Conserved Sequence; Databases, Factual; DNA Primers; DNA, Complementary; Humans; Immune-related protein; Invertebrate immunity; Marine; Membrane Glycoproteins - chemistry; Membrane Glycoproteins - genetics; Mice; Molecular Sequence Data; Polymerase Chain Reaction; Pregnancy Proteins - chemistry; Pregnancy Proteins - genetics; Proteins - chemistry; Proteins - genetics; Rabbits; Repetitive Sequences, Nucleic Acid; Sequence Homology, Amino Acid; Short consensus repeats; TNF-α; Tumor Necrosis Factor-alpha - chemistry; Tumor Necrosis Factor-alpha - genetics; Tunicates; Urochordata - chemistry; Urochordata - genetics; Vertebrata; Vitronectin - chemistry; Vitronectin - genetics; Tunicates; Botryllus schlosseri; Invertebrate immunity; TNF-α; Immune-related protein; Complement; Ascidiacea; Short consensus repeats
• ISSN: 1096-4959; 0305-0491; 1879-1107
• DOI: 10.1016/0305-0491(95)00025-4

Mammalian tumor necrosis factor (TNF)-α 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-α, 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 as similarity (up to 50.5%) of Bs.l 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.