Structure of the human gene encoding the invariant γ-chain of class II histocompatibility antigens

Abstract

The primary structures of a cDNA and the genomic DNA of a gene selectively expressed in chronic lymphocytic leukemia were determined. A computer search of the nucleotide sequence data bank identified this gene as the invariant gamma-chain associated with class II histocompatibility antigens. The invariant gamma-chain genomic sequence spans about 11 kilobases, with eight exons and seven introns. Three of the introns contain members of the Alu repeat family. A putative cap site and promoter sequence were identified at the 5' end of the gene. One or two copies of the gene is present in each haploid genome, and no evidence for amplification or polymorphism was obtained.

Alternative splicing and alternative initiation of translation explain the four forms of the Ia antigen-associated invariant chain.

“…From this experiment, we concluded that clone p41-1 was derived from a mature mRNA, called p41 mRNA, which has the capacity to direct the synthesis of a protein related to the p33 In chain. p41 mRNA is the result of a differential splicing event Southern blot data and analysis of genomic clones have supported the existence of a single In chain gene (Kudo et al, 1985;and unpublished). From a comparison ofthe sequence of p41-1 cDNA with the In chain gene sequence published by Kudo et al (1985), we observed that the position corresponding to the boundary of the additional segment of clone p41-1 is precisely at the splice junctions between exon 6 and exon 7.…”

“…p41 mRNA is the result of a differential splicing event Southern blot data and analysis of genomic clones have supported the existence of a single In chain gene (Kudo et al, 1985;and unpublished). From a comparison ofthe sequence of p41-1 cDNA with the In chain gene sequence published by Kudo et al (1985), we observed that the position corresponding to the boundary of the additional segment of clone p41-1 is precisely at the splice junctions between exon 6 and exon 7. Moreover, the complete sequence of the additional intervening segment of clone p41-1 was found in the sequence of the genomic clone within the intron separating exons 6 and 7, 1353 bp from the 3' end of exon 6 (Kudo et al, 1985; Figure 2B).…”

“…From a comparison ofthe sequence of p41-1 cDNA with the In chain gene sequence published by Kudo et al (1985), we observed that the position corresponding to the boundary of the additional segment of clone p41-1 is precisely at the splice junctions between exon 6 and exon 7. Moreover, the complete sequence of the additional intervening segment of clone p41-1 was found in the sequence of the genomic clone within the intron separating exons 6 and 7, 1353 bp from the 3' end of exon 6 (Kudo et al, 1985; Figure 2B). p41 mRNA contains therefore an additional coding region, encoded in an additional exon denoted 6b ( Figure 4A).…”

“…Comparison of this clone with the sequence of the In chain gene deduced from genomic clones (Kudo et al, 1985) revealed that the sequence corresponding to the additional segment in the p41 cDNA is located within the intron between exon 6 and exon 7 of the genomic sequence published by Kudo et al (1985). One can therefore refer to that segment as exon 6b.…”

Sequence investigation of the major gastrointestinal tumor-associated antigen gene family, GA733.

“…The GA733 genes are related to the HLA-DR-associated invariant chain gene (25,26), in that exon 6b of this gene (27) is homologous to the second type I repeat of thyroglobulin, and the second and fourth type I repeats derive from an ancestral 60-amino acid unit (24). The relationships among these three genes are depicted in Fig.…”