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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Chordata, Nonvertebrate / genetics
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Chordata, Nonvertebrate / immunology*
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Cloning, Molecular
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Complement Activation* / genetics
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Complement C1r / chemistry
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Complement C1r / genetics
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Complement C1r / physiology
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Complement C1s / chemistry
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Complement C1s / genetics
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Complement C1s / physiology
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Consensus Sequence
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DNA, Complementary / isolation & purification
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Evolution, Molecular*
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Genes
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Isoenzymes / chemistry
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Isoenzymes / genetics
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Isoenzymes / isolation & purification
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Isoenzymes / physiology
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Lampreys / genetics
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Lampreys / immunology
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Lectins / metabolism*
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Mannose / metabolism*
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Mannose-Binding Protein-Associated Serine Proteases
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Molecular Sequence Data
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Multigene Family / genetics
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Multigene Family / immunology
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Phylogeny
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Sequence Homology, Amino Acid
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Serine Endopeptidases / chemistry
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Serine Endopeptidases / genetics
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Serine Endopeptidases / isolation & purification*
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Serine Endopeptidases / physiology*
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Urochordata / genetics
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Urochordata / immunology
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Xenopus / genetics
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Xenopus / immunology
Substances
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DNA, Complementary
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Isoenzymes
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Lectins
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Mannose-Binding Protein-Associated Serine Proteases
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Serine Endopeptidases
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Complement C1r
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Complement C1s
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Mannose
Associated data
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GENBANK/AB078636
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GENBANK/AB078637
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GENBANK/AB078885
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GENBANK/AB078886
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GENBANK/AB078887
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GENBANK/AB078888
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GENBANK/AB078889
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GENBANK/AB078890
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GENBANK/AB078891
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GENBANK/AB078892
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GENBANK/AB078893
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GENBANK/AB078894
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GENBANK/AB078907
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GENBANK/AB078908
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GENBANK/AB078909
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GENBANK/AB089265
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GENBANK/AB089266
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GENBANK/AB089267
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GENBANK/AB089268
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GENBANK/AB089507