Gene structures of rat cathepsins H and L

The gene structures of rat cathepsins H and L have been determined. Cathepsin H gene spans more than 21.5 Kbp and comprises more than 12 exons. On the other hand, cathepsin L gene spans 8.5 Kbp and comprises 8 exons. In both genes, two intron insertion positions are conserved at the amino acid level. Both enzymes, therefore, diverged from a common ancestral gene. In the 5'-upstream region of the cathepsin L gene, no TATA box, one CAAT box and some SP-1 binding sites exist, common with other lysosomal enzyme genes. Furthermore, two AP-2 binding sites exist: a promoter under the control by the tumor promoter (TPA) and cAMP, and a cAMP response element (CRE). These results suggest that the cathepsin L gene expression is controlled by these factors.