Structure and organization of theC4genes

Abstract

This 200000M_rserum protein is coded for by at least two separate loci,C4AandC4B, which map in the HLA Class III region on chromosome 6 in man. Both loci are highly polymorphic with more than 30 alleles, including null alleles assigned to the two loci. The complete nucleotide sequence of a full length C4A cDNA clone and a substantial part of a C4B cDNA clone has shown class differences which can be used to synthesize nucleotide probes specific for C4A and C4B. ThreeC4loci of approximately 16 kilobases each spaced by 10 kilobases have been identified in DNA from one individual and aligned 30 kilobases from thefactor Bgene by overlapping cloned genomic fragments from a cosmid library. Characterization of these genes by restriction mapping, nucleotide sequence analysis and hybridization with C4A and C4B specific synthetic oligonucleotides show that these genes are very similar.