The genomic organization of Isopeptidase T-3 (ISOT-3), a new member of the ubiquitin specific protease family (UBP).

A novel Isopeptidase T gene (ISOT-3) has been identified on human mosome 3q26.2--q26.3. gene shows 67.3% nucleotide identity and 54.8% amino acid identity to n Isopeptidase (ISOT-1). Northern blot analysis has shown that ISOT-3 is highly essed in ovary and testes, low-level expression in six other tissues tested. In contrast, ISOT-1 is essed at high levels in brain, and there is no detectable expression in ovary. The exonic nization of these two genes highly conserved with only one variant intron position. Intron 15 in -3 is absent in ISOT-1, there is an alternate splice site at the same location. Although the --intron structure has been erved between the two genes, ISOT-3 has significantly larger intronic ons, and the overall of this gene is at least 90 kb compared to 15 kb for ISOT-1. These data suggest that both ISOT-1 and ISOT-3 have descended from a common ancestor. In addition, the low overall sequence identity and different expression patterns may reflect differences in substrate specificity.