Molecular cloning of the complement regulatory factor I isotypes from the common carp (Cyprinus carpio).
Factor I is a novel serine protease that regulates complement activation. Here we report the complete primary structure of two isotypic factor Is isolated from the common carp ( Cyprinus carpio), a pseudotetraploid teleost. A carp hepatopancreas cDNA library was screened using two RT-PCR-amplified cDNA fragments encoding part of the carp factor I-like serine protease domain. Two distinct cDNA clones, designated FI-A and FI-B, were isolated. Their deduced amino acid sequences share 75.2% identity with each other. FI-A has a typical factor I-like domain organization composed of two disulfide-linked polypeptides (H-chain and L-chain). On the other hand, FI-B contains a novel sequence of 115 amino acids inserted at the N-terminus of the H-chain. Genomic Southern hybridization suggests that FI-A and FI-B are encoded by distinct genes in the carp genome. Expression analysis by RT-PCR revealed that the major site of FI-A expression is the ovary, whereas FI-B expression is detected mainly in the hepatopancreas at a level higher than that of FI-A. The present data, taken together, suggest that carp have duplicated genes coding for factor I, and FI-B with the novel insertion plays a dominant role in the complement system. In addition, homology search of the fugu genome database using the carp FI-A and FI-B sequences identified a putative fugu factor I gene, which has an exon/intron organization different from that of the human orthologue.
Nakao
Miki
M
Laboratory of Marine Biochemistry, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Hakozaki, 812-8581 Fukuoka, Japan. miki_n@agr.kyushu-u.ac.jp
Hisamatsu
Satomi
S
Nakahara
Makiko
M
Kato
Yoko
Y
Smith
Sylvia L
SL
Yano
Tomoki
T
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002347:Carps / Q000235:genetics* / Q000276:immunology*; D003001:Cloning, Molecular; D017244:Complement Factor I / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D005091:Exons; D020440:Gene Duplication; D007438:Introns; D007527:Isoenzymes / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D023741:Takifugu / Q000235:genetics / Q000276:immunology
D018076:DNA, Complementary; D007527:Isoenzymes; D017244:Complement Factor I