Molecular map of the murine S region.
Eighteen overlapping cosmid clones spanning 240 kilobases and encoding the gene for factor B and two genes related to the fourth component of complement (C4) were isolated from a murine H-2d genomic library. Cosmid clones were identified by hybridization to human cDNA probes for factor B and C4 and were linked by chromosomal walking procedures. The cluster of clones contains two regions with sequences homologous to the C4 cDNA probe, both in the same orientation, representing a direct duplication of at least 55 kilobases of chromosomal DNA, separated by a shorter (less than 25 kilobases) segment of nonduplicated DNA. Restriction fragment-length polymorphism seen by using C4 probes maps these sequences to the S region of the major histocompatibility complex. 5' to the two C4-like sequences is an approximately equal to 40-kilobase-long region of chromosomal DNA remarkable for its lack of restriction fragment-length polymorphism, containing sequences homologous to the human factor B cDNA probe. These experiments demonstrate that the structural gene for factor B is located in the S region of the murine major histocompatibility complex and that this region contains an extensive direct duplication that contains the structural gene for mouse C4 and, we presume, for the sex-limited protein variant, Slp. RNA transfer blot analysis of total liver RNA from high C4- and low C4-producing strains showed that steady-state levels of C4-hybridizing RNA were much greater in high C4-producing strains. Regulation of circulating C4 levels in high C4 and low C4 strains is at least partly at the level of mRNA transcription, processing, or degradation.
Chaplin M.D., Ph.D., David
Proceedings of the National Academy of Sciences Journal
Animals, Base Composition, Base Sequence, Chromosome Mapping, Cloning, Molecular, DNA, DNA Restriction Enzymes, Humans, Mice, Nucleic Acid Hybridization, Plasmids
10.1073/pnas.80.22.6947
Chaplin DD; Woods DE; Whitehead AS; Goldberger G; Colten HR; Seidman JG