We cloned and analyzed a complement regulatory protein cDNA (designated HCRF) from the Japanese flounder Paralichthys olivaceus. The length of the cDNA obtained was 1662 bp. The predicted translation product represents a protein of 453 amino acids which displays a putative hydrophobic leader sequence. There were 7 short consensus repeats (SCRs) which are closely related to those of the previously described SBP1 and SBCFR-1 of complement regulatory plasma proteins of barred sand bass Paralabrax neblifer. The SCRs of HCRF, SBP1, and SBCFR-1 constitute 7, 17, and 3 domains, respectively. SCR domains Nos. 2 to 7 of HCRF resembled domains Nos. 12 to 17 of SBP1. SCR domains Nos. 6 and 7 of HCRF also closely resembled domains Nos. 2 and 3 of SBCFR-1, respectively.
The expression of the complement regulatory protein-like mRNA in flounder liver was demonstrated by Northern blot hybridization.