Isolation and analysis of genomic DNA clones encoding the third component of mouse complement.

Abstract

A gene library was constructed with DNA from strain A mice by using the phage .lambda. vector .lambda. 1059. By screening with cloned c[complementary]DNA for the 3rd component of mouse complement, C3, 4 different C3 genomic clones were isolated from this library. Two of the recombinant phages carry insertions of 14 and 18 kilobase pairs, respectively, which together cover one complete copy of the C3 gene and several hundred nucleotides of its 5'' and 3'' flanking sequences. The distance from the 5'' end of the gene, which includes the hexanucleotide T-A-T-A-A-A and a translation initiation codon, to its 3'' end as defined by the poly(A) attachment site is 24 kilobase pairs. From the genomic DNA sequence, a signal peptide of 24 amino acid residues is predicted at the NH2 terminus of the initial translation product. The signal peptide and the next 2 amino acids are encoded by the 1st exon of this gene.