Sequencing and genetic analysis of a bovine DQB cDNA clone.
A BoLA-DQB cDNA clone (BoLA-DQ beta-1) was isolated by screening a bovine lymphoblastoid cDNA library with a HLA-DQB genomic clone. The DNA and predicted protein sequences were compared to class II sequences from cattle and other species. BoLA-DQ beta-1 has 92.0% similarity to the coding regions of two previously sequenced BoLA-DQB genomic clones and 69.6% similarity to a BoLA-DR beta pseudogene. However, the first domain encoded by BoLA-DQ beta-1 has 94 amino acids; one more than the predicted size of the products encoded by two previously sequenced bovine DQB genes (BoDQ beta-Q1 and BoDQ beta-Y1). Comparing all coding regions, BoLA-DQ beta-1 has greater nucleotide similarity to HLA-DQB sequences than to I-A beta, HLA-DRB and I-E beta sequences. Like the HLA-DQB gene product, the cytoplasmic domain of the predicted protein encoded by BoLA-DQ beta-1 is eight amino acids shorter than that of I-A beta, HLA-DRB and I-E beta molecules. Six clone-specific amino acid substitutions were identified in the beta 1 domain of BoLA-DQ beta-1, including an unusual cysteine residue at position 13 which is believed to be positioned on a beta-strand and face into the antigen recognition site. Southern blot analysis of PvuII-digested genomic DNA from a paternal half-sibling family (sire, and six dam-offspring pairs) using BoLA-DQ beta-1 as a probe, revealed five allelic PvuII RFLP patterns, including two patterns not previously described, that cosegregated with serologically-defined BoLA-A (class I) alleles. The evolution, polymorphism and function of a transcriptionally active BoLA-DQB gene can now be readily studied using this DQB cDNA clone as a source of allele and locus-specific oligonucleotide primers.
Xu
A
A
Department of Animal Sciences, University of Illinois, Urbana-Champaign.
Clark
T J
TJ
Teutsch
M R
MR
Schook
L B
LB
Lewin
H A
HA
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle / Q000235:genetics* / Q000276:immunology*; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics*; D005802:Genes, MHC Class II; D006683:HLA-DQ Antigens / Q000235:genetics; D059866:HLA-DQ beta-Chains; D006801:Humans; D008969:Molecular Sequence Data; D011110:Polymorphism, Genetic; D021382:Protein Sorting Signals / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
D006683:HLA-DQ Antigens; D059866:HLA-DQ beta-Chains; C057615:HLA-DQbeta antigen; D021382:Protein Sorting Signals; D004247:DNA