Analysis of DRβ and DQβ cDNA clones from a DR7 haplotype
1
Abstracts 179 The DRw52 serologic specificity is in linkage disequilibrium with the DR3, -5, and -w6 specificities, presumably because the DR3, -5, and -w6 haplotypes share a similar if not identical DRfl2 chain. In contrast, the DQ serologic specificities, which are probably encoded by DQfl chains display a different pattern of linkage disequilibrium with DR: DRw6 is DQwl, DR3 is DQw2, and DR5 is DQw3. However, DQa polymorphism, as detected by Southern blot analysis, follows the DRw52 pattern. In order to resolve this paradox we have isolated and se- quenced class II cDNA clones from a DR5 cell line, EPA, which types as DR5, DRw52, DQwl. With the exception of minor differences at position 86, the DRIll chain from EPA is identical to a previously published DRIll from a DR5, DQw3 haplotype. The DQa sequence is identical to DQa from a DRw6, DRw52 haplotype. Thus, the common evolutionary origin of DR3, DR5, and DRw6 haplotypes as suggested by the DRw52 serologic data, is confirmed by the identity of DQa genes from DR5 and DRw6 haplotypes. This DQa allele is maintained in linkage disequilibrium with DRw52 and DR3,5, and w6 specificities because of a lack of recombination between DRfl and DQa. In contrast, the lack of similarity of DQfl in DR3,5 and w6 haplotypes suggest that DQfl is not part of the genetic unit defined by DRw52, possibly because of recombination. In this regard, partial DQI3 sequence from the EPA cell line suggests that it is closely related to the DQ3 molecule from a DR2 cell line. Thus, the EPA haplotype may have arisen by recombination between a DR2 haplotype and a DR5 hap- lotype. Such recombination events would appear to take place between the DQa and DQfl loci. ANALYSIS OF DRfl AND DQ3 cDNA CLONES FROM A DR7 HAPLOTYPE. Robert Karr, Peter Gregersen, and Jack Silver; Hospital for Joint Diseases, New York, N Y and VA Medical Center and University of Iowa, Iowa City, IA A cDNA library was constructed from a DR7, DRw53, DQw2 homozygous cell line, cDNA clones corresponding to DR 3 and DQ,8 chains were isolated, and the nucleotide sequences of the polymorphic first domains were determined in order to compare the DRw53-associated DRfl chain with the analogous chain from a DR4 cell and the DQw2-associated DQfl chain with the analogous chain from a DR3 cell. A novel screening strategy allowed rapid and simple identifi- cation of cDNA clones corresponding to both DRfl chains (DR7fll and DR7fl2) prior to sequencing; DR7fl2 clones have a recognition site for the enzyme BssHII, whereas DR7fll clones do not. The DR7fll sequence differs from the sequences of all previously reported DRfl chains. As predicted by the presence of the BssHII site in the DR7fl2 clone, the DR7fl2 sequence differs from the DR7fll sequence. The DR7/31 and DRTfl2 first domain sequences have 84% nucleotide sequence homology. They differ at 46 positions, 38 of which result in 24 amino acid substitutions. Importantly, the sequence of the DRw53-associated DR7fl2 chain is identical to the reported sequence of the DRw53-associated DR4fl2 chain. In addition, the sequence of the DQ,8 chain from the DR7, DQw2 cell line is identical to the reported sequence of a DQfl chain from a DR3, DQw2 cell. These findings raise interesting questions about the evolution of the DR3, DR4, and DR7 haplotypes. CHARACTERIZATION OF TWO DISTINCT DRfl CHAIN ALLELES AT THE flIIl LOCUS OF THE DR5 HAPLOTYPE. J. Schiffenbauer, D. Didier, S. Shuman, V. Tieber, and B.D. Schwartz; HHMI and Washington University School of Medicine, St. Louis, MO
Transcript of Analysis of DRβ and DQβ cDNA clones from a DR7 haplotype
Abstracts 179
The DRw52 serologic specificity is in linkage disequilibrium with the DR3, -5, and -w6 specificities, presumably because the DR3, -5, and -w6 haplotypes share a similar if not identical DRfl2 chain. In contrast, the DQ serologic specificities, which are probably encoded by DQfl chains display a different pattern of linkage disequilibrium with DR: DRw6 is DQwl, DR3 is DQw2, and DR5 is DQw3. However, DQa polymorphism, as detected by Southern blot analysis, follows the DRw52 pattern. In order to resolve this paradox we have isolated and se- quenced class II cDNA clones from a DR5 cell line, EPA, which types as DR5, DRw52, DQwl. With the exception of minor differences at position 86, the DRIll chain from EPA is identical to a previously published DRIll from a DR5, DQw3 haplotype. The DQa sequence is identical to DQa from a DRw6, DRw52 haplotype. Thus, the common evolutionary origin of DR3, DR5, and DRw6 haplotypes as suggested by the DRw52 serologic data, is confirmed by the identity of DQa genes from DR5 and DRw6 haplotypes. This DQa allele is maintained in linkage disequilibrium with DRw52 and DR3,5, and w6 specificities because of a lack of recombination between DRfl and DQa. In contrast, the lack of similarity of DQfl in DR3,5 and w6 haplotypes suggest that DQfl is not part of the genetic unit defined by DRw52, possibly because of recombination. In this regard, partial DQI3 sequence from the EPA cell line suggests that it is closely related to the DQ3 molecule from a DR2 cell line. Thus, the EPA haplotype may have arisen by recombination between a DR2 haplotype and a DR5 hap- lotype. Such recombination events would appear to take place between the D Q a and DQfl loci.
ANALYSIS OF DRfl AND DQ3 cDNA CLONES FROM A DR7 HAPLOTYPE. Robert Karr, Peter Gregersen, and Jack Silver; Hospital for Joint Diseases, New York, N Y and VA Medical Center and University of Iowa, Iowa City, IA
A cDNA library was constructed from a DR7, DRw53, DQw2 homozygous cell line, cDNA clones corresponding to DR 3 and DQ,8 chains were isolated, and the nucleotide sequences of the polymorphic first domains were determined in order to compare the DRw53-associated DRfl chain with the analogous chain from a DR4 cell and the DQw2-associated DQfl chain with the analogous chain from a DR3 cell. A novel screening strategy allowed rapid and simple identifi- cation of cDNA clones corresponding to both DRfl chains (DR7fll and DR7fl2) prior to sequencing; DR7fl2 clones have a recognition site for the enzyme BssHII, whereas DR7fll clones do not. The DR7fll sequence differs from the sequences of all previously reported DRfl chains. As predicted by the presence of the BssHII site in the DR7fl2 clone, the DR7fl2 sequence differs from the DR7fll sequence. The DR7/31 and DRTfl2 first domain sequences have 84% nucleotide sequence homology. They differ at 46 positions, 38 of which result in 24 amino acid substitutions. Importantly, the sequence of the DRw53-associated DR7fl2 chain is identical to the reported sequence of the DRw53-associated DR4fl2 chain. In addition, the sequence of the DQ,8 chain from the DR7, DQw2 cell line is identical to the reported sequence of a DQfl chain from a DR3, DQw2 cell. These findings raise interesting questions about the evolution of the DR3, DR4, and DR7 haplotypes.
CHARACTERIZATION OF TWO DISTINCT DRfl CHAIN ALLELES AT THE flIIl LOCUS OF THE DR5 HAPLOTYPE. J. Schiffenbauer, D. Didier, S. Shuman, V. Tieber, and B.D. Schwartz; HHMI and Washington University School of Medicine, St. Louis, MO
