Ahr^d

This allele encodes a 104 kDa receptor that is stabilized by molybdate and has an affinity for ligand 10-100 fold lower than that of the receptor produced by the C57BL/6J allele. PCR sequencing of cDNA revealed ten nucleotide differences between the coding sequences of the DBA/2J and C57BL/6J receptors. Five of the ten differences would cause amino acid changes. One of these, an apparent T to C transition replaces the opal termination codon in the C57BL/6J allele with an arginine codon in the DBA/2J allele. This change would extend translation of the DBA/2J mRNA by 43 amino acids, accounting for the larger size of the peptide produced by this allele (104 kDa vs 95 kDa for the C57BL/6J allele). A second T to C transition changes a leucine codon in the C57BL/6J allele to a proline codon in the DBA/2J allele, and would likely change secondary structure of the peptide and thus ligand affinity. (J:15153, J:17460, J:22144)