title: Isolation of cDNA clones specifying the fourth component of mouse complement and its isotype, sex-limited protein.
abstract: cDNA clones specific for the fourth component of mouse complement (C4) and its hormonally regulated isotype, sex-linked protein (Slp), were isolated using as a probe a 20-mer synthetic oligonucleotide corresponding to a known sequence of human C4 cDNA. Two types of clones, one specific for C4 (pFC4/10, with a 3.7 kilobase insert) and one specific for Slp (pFSlp/1, with a 4.7 kilobase insert), were isolated from liver cDNA libraries constructed from the Slp-producing FM mouse strain. The cDNA inserts of these clones shared 70% of the restriction sites determined. Only one type of clone was isolated from the Slp-negative DBA/1 strain; this type showed restriction maps indistinguishable from that of pFC4/10. pFC4/10 and pFSlp/1 displayed extensive homology: 94% nucleotide homology and 89% derived amino acid homology in the C4a region and 92% nucleotide homology and 89% derived amino acid homology in the thiol-ester region. An Arg-Gln-Lys-Arg sequence in the beta-alpha junction and a Cys-Ala-Glu-Gln sequence in the thiol-ester site were identified for both proteins. A remarkable divergency between C4 and Slp sequences was recognized in the region immediately following the C4a sequence.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001798:Blood Proteins / Q000235:genetics*; D003181:Complement C4 / Q000235:genetics*; D004247:DNA / Q000302:isolation & purification*; D004274:DNA, Recombinant; D005260:Female; D008099:Liver / Q000032:analysis; D008297:Male; D051379:Mice; D008811:Mice, Inbred DBA; D009693:Nucleic Acid Hybridization; D011061:Poly A; D012313:RNA; D012333:RNA, Messenger
chemical_list: D001798:Blood Proteins; C018386:C4a protein, mouse; D003181:Complement C4; D004274:DNA, Recombinant; D012333:RNA, Messenger; D011061:Poly A; D012313:RNA; D004247:DNA