Evidence for heterogeneity of the DPA and DPB alleles derived from a DRw11,DQw7,DPw4 cell line.

We have previously reported the complete sequence of the cDNAs corresponding to the alleles at the polymorphic loci (DRB1, DRB3, DQA1, DQB1) of the DRw11(5) cell line Swei. We now report the nucleotide and derived amino acid sequence of the alleles at the remaining two polymorphic loci, DPA1 and DPB1, from Swei, which types as DPw4b. Comparison of the DPw4b alpha sequence with previous DP alpha sequences indicates that it is identical to the DP alpha chains of DPw4 and DPw2. However, the DPw4b alpha cDNA encodes a unique 3' untranslated region that corresponds to sequences contained within the last intron of the DP alpha genomic gene. These results indicate that alternative splicing occurs within the Swei DP alpha RNA. Comparison of the DPw4b beta sequence with previously reported DP beta sequences indicates that the first domain is identical to the sequence of the DP beta chain derived from the Burkhardt (Burk) cell line, but that the second domain differs by two amino acids. In addition, a single amino acid difference from DPw2 at position 69 in the first domain of the DPw4b beta chain suggests that this residue is important in determining DP specificity. Furthermore, comparison with other DP beta DNA sequences suggests that variable regions occur at positions 8-11, 55-57, and 84-87.