Title : Nucleotide and predicted amino acid
sequences of cloned human and mouse
preprocathepsin B cDNAs
Abstract :
- Cathepsin B is a lysosomal thiol proteinase that may have additional extralysosomal functions
- To further our investigations on the structure, mode of biosynthesis, and intracellular sorting of this enzyme, we have determined the complete coding sequences for human and mouse preprocathepsin B by using cDNA clones isolated from human hepatoma and kidney phage libraries
- The nucleotide sequences predict that the primary structure of preprocathepsin B contains 339 amino acids organized as follows: a 17-residue NH2-terminal prepeptide sequence followed by a 62-residue propeptide region , 254 residues in mature (single chain) cathepsin B , and a 6-residue extension at the COOH terminus
- A comparison of procathepsin B sequences from three species (human, mouse, and rat) reveals that the homology between the propeptides is relatively conserved with a minimum of 68% sequence identity
- In particular, two conserved sequences in the propeptide that may be functionally significant include a potential glycosylation site and the presence of a single cysteine at position 59
- Comparative analysis of the three sequences also suggests that processing of procathepsin B is a multistep process, during which enzymatically active intermediate forms may be generated
- The availability of the cDNA clones will facilitate the identification of possible active or inactive intermediate processive forms as well as studies on the transcriptional regulation of the cathepsin B gene