DNA sequence of a class I pseudogene from theTla region of the murine MHC: Recombination at a B2 Alu repetitive sequence

Summary We have determined the DNA sequence of a BALB/cTla region class I gene from the major histocompatibility complex (MHC) that had been identified previously as encoding a murine antigen by DNA-mediated gene transfer. Analysis of the DNA sequence shows, however, that this gene, the T1^c gene from theTla^c genotype, could not encode a TL antigen or any other functional class I molecule due to the presence of numerous stop codons and frameshift mutations in the coding regions. This result suggests that the earlier transformation data may have been incorrect or perhaps that the clone containing the T1^c gene contains sequences that induced expression of a serologically reactiveTla gene in the genome of the recipient L cell. The T1^c gene is structurally related to the previously sequenced T13^c gene that encodes a serologically defined TL antigen. The 3 half of the T1^c gene including exons 4, 5, 6, and the 3 untranslated region has about 85% nucleotide similarity (including introns) with the corresponding parts of the T13^c gene; however, the 5 half of the T1^c gene has little homology with the T13^c gene. There is a sharp line of demarcation between the homologous and nonhomologous regions, and this border occurs precisely at a B2 Alu repeat sequence present in the T13^c gene. This suggests that a recombination event took place here and that an Alu repeat sequence that is known to have characteristics of transposable elements played some role in a recombination or gene conversion event.