A 100-kDa protein in the C4-activating component of Ra-reactive factor is a new serine protease having module organization similar to C1r and C1s.

• DOI: 10.4049/jimmunol.152.5.2308
• Publication Date: 2022-12-31T12:27:41Z
• Authors: Y Takayama; F Takada; A Takahashi; M Kawakami
• Keywords: Mice, Inbred ICR; 0303 health sciences; DNA, Complementary; Base Sequence; Complement C1s; Sequence Homology, Amino Acid; Complement C1r; Molecular Sequence Data; Gene Expression; Complement C4; Molecular Weight; Mice; 03 medical and health sciences; Cricetinae; Mannose-Binding Protein-Associated Serine Proteases; Animals; Humans; Amino Acid Sequence; RNA, Messenger; Cloning, Molecular; Complement Activation; DNA Primers

Ra-reactive factor (RaRF), a C-dependent bactericidal in mice, is composed of one polysaccharide-binding component and C4/C2-activating component. The former an oligomer 28-kDa protein corresponding to the mannose-binding mice. 100-kDa protein, P100, has been shown be present This generates 29- 70-kDa polypeptide chains when reduced. In this study, we determined nucleotide sequence cDNA coding for P100. cDNAs were prepared by reverse transcription PCR cassette-ligation-mediated on mRNA from BALB/c mouse liver, using primers synthesized reference previous study. results sequencing indicate that precursor P100 containing 24-residue signal peptide consists 704 amino acid residues. Taking electrophoretic study into consideration, it thought cleavage mature 29-kDa chain 251 residues 429 Although homology with human C1r C1s subcomponents C was less than 40%, striking similarity domain organization found among these proteins, indicating new C4-activating serine protease structurally similar C1s. Northern hybridization showed liver primary site expression gene.