Cloning and sequencing of full-length cDNA encoding the precursor of human complement component C1r.

The sequencing of human liver cDNA clones encoding the entire C1r precursor protein has confirmed the previously determined peptide sequence and has shown that there is a leader peptide which is 17 amino acids long. A residue tentatively identified as beta-hydroxyaspartic acid [Arlaud, Willis & Gagnon (1986) Biochem. J., in the press] located in the C1r A-chain, within an epidermal-growth-factor consensus sequence, was found to be encoded as asparagine. Two sequence elements, tandemly located in the A-chain, are related to a sequence widespread among proteins which interact with C3b or C4b. Structural comparisons between different clones indicate that multiple polyadenylation sites are responsible for the length heterogeneity observed for C1r mRNA from liver and Hep G2 cells.