title: Rat procathepsin B. Proteolytic processing to the mature form in vitro.
abstract: Expression of rat procathepsin B in yeast led to the secretion of both the latent and mature forms of the enzyme. Culture in the presence of a cysteine proteinase inhibitor prevented this processing. We have expressed and purified a mutant form of rat procathepsin B whose active-site cysteine residue has been changed to a serine, and which also lacks the glycosylation site in the mature region of the protein. This non-active mutant protein was secreted essentially in an unprocessed form. The purified protein has been incubated with a variety of proteinases, and results indicate that cathepsins D and L, as well as mature cathepsin B itself, can produce a processed (single-chain) form of cathepsin B from this precursor. Amino-terminal sequencing of these processed forms has revealed that they are all elongated by a few residues with respect to the mature form found in vivo. The action of a combination of cathepsin B with dipeptidylpeptidase I produced a single-chain form of cathepsin B with the correct amino terminus. This work has also shown that the processing of procathepsin B to a single-chain form can be an autocatalytic process, in at least an intermolecular manner.
authors.affiliation: Joint Diseases Laboratory, Shriners Hospital for Crippled Children, Montreal, Quebec, Canada.
authors.forename: A D
authors.initials: AD
authors.lastname: Rowan
authors.forename: P
authors.initials: P
authors.lastname: Mason
authors.forename: L
authors.initials: L
authors.lastname: Mach
authors.forename: J S
authors.initials: JS
authors.lastname: Mort
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002401:Cathepsin B / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000378:metabolism; D004792:Enzyme Precursors / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D011499:Protein Processing, Post-Translational; D051381:Rats; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D013379:Substrate Specificity
chemical_list: D004792:Enzyme Precursors; D009838:Oligodeoxyribonucleotides; D011994:Recombinant Proteins; D010450:Endopeptidases; C057832:procathepsin B; D002401:Cathepsin B