title: Origin of mannose-binding lectin-associated serine protease (MASP)-1 and MASP-3 involved in the lectin complement pathway traced back to the invertebrate, amphioxus.
abstract: Mannose-binding lectin-associated serine proteases (MASPs) are involved in complement activation through the lectin pathway. To elucidate the phylogenetic origin of MASP and a primordial complement system, we cloned two MASP cDNAs from amphioxus (Branchiostoma belcheri) of the cephalochordates, considered to be the closest relative of vertebrates. The two sequences, orthologues of mammalian MASP-1 and MASP-3, were produced by alternative processing of RNA from a single gene consisting of a common H chain-encoding region and two L chain-encoding regions, a structure which is similar to that of the human MASP1/3 gene. We also isolated two MASP genes from the ascidian Halocynthia roretzi (urochordates) and found that each of them consists simply of an H chain-encoding region and a single L chain-encoding region. The difference in structure between the ascidian MASP genes and the amphioxus/mammalian MASP genes suggests that a prototype gene was converted to the MASP1/3-type gene possessing two L chain-encoding regions at an early stage of evolution before the divergence of amphioxus. This conclusion is supported by the presence of MASP-1 and MASP-3 homologues in almost all vertebrates, as demonstrated by the cloning of novel cDNA sequences representing lamprey (cyclostomes) MASP-1 and Xenopus MASP-3. The ancient origin of MASP-1 and MASP-3 suggests that they have crucial functions common to all species which emerged after cephalochordates.
authors.affiliation: Department of Biochemistry, Fukushima Medical University School of Medicine, Fukushima, Japan. yendo@fmu.ac.jp
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Endo
authors.forename: Masaru
authors.initials: M
authors.lastname: Nonaka
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Saiga
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kakinuma
authors.forename: Akiko
authors.initials: A
authors.lastname: Matsushita
authors.forename: Minoru
authors.initials: M
authors.lastname: Takahashi
authors.forename: Misao
authors.initials: M
authors.lastname: Matsushita
authors.forename: Teizo
authors.initials: T
authors.lastname: Fujita
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002816:Chordata, Nonvertebrate / Q000235:genetics / Q000276:immunology*; D003001:Cloning, Molecular; D003167:Complement Activation / Q000235:genetics; D015923:Complement C1r / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D003173:Complement C1s / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D016384:Consensus Sequence; D018076:DNA, Complementary / Q000302:isolation & purification; D019143:Evolution, Molecular; D005796:Genes; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D007798:Lampreys / Q000235:genetics / Q000276:immunology; D037102:Lectins / Q000378:metabolism*; D008358:Mannose / Q000378:metabolism*; D050606:Mannose-Binding Protein-Associated Serine Proteases; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics / Q000276:immunology; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology*; D014561:Urochordata / Q000235:genetics / Q000276:immunology; D014981:Xenopus / Q000235:genetics / Q000276:immunology
chemical_list: D018076:DNA, Complementary; D007527:Isoenzymes; D037102:Lectins; D050606:Mannose-Binding Protein-Associated Serine Proteases; D012697:Serine Endopeptidases; D015923:Complement C1r; D003173:Complement C1s; D008358:Mannose