Degradation of fructose-1,6-bisphosphate aldolase by cathepsin B.
The mechanism of degradation of fructose-1,6-bisphosphate aldolase from rabbit muscle by the lysosomal proteinase cathepsin B was determined. Treatment of aldolase with cathepsin B destroys up to 90% of activity with fructose 1,6-bisphosphate as substrate, but activity with fructose 1-phosphate is slightly increased. Cathepsin L, another lysosomal thiol proteinase, and papain are also potent inactivators of aldolase, whereas inactivation is not caused by cathepsins D or H even at high concentrations, or by cathepsin B inhibited by leupeptin or iodoacetate. The cathepsin-B-treated aldolase shows no detectable change in subunit molecular weight, oligomer molecular weight or subunit interactions. Cathepsin B cleaves dipeptides from the C-terminus of th aldolase subunits. Four dipeptides are released sequentially: Ala-Tyr, Asn-His, Ile-Ser and Leu-Phe, and a maximum of five additional dipeptides may be released. There are indications that this peptidyldipeptidase activity of cathepsin B may be an important aspect of its action on protein substrates generally.
D000596:Amino Acids / Q000032:analysis; D002403:Cathepsins / Q000378:metabolism*; D004150:Dipeptidases / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005634:Fructose-Bisphosphate Aldolase / Q000378:metabolism*; D005636:Fructosephosphates / Q000378:metabolism; D010455:Peptides / Q000032:analysis
D000596:Amino Acids; D005636:Fructosephosphates; D010455:Peptides; D002403:Cathepsins; D004150:Dipeptidases; D005634:Fructose-Bisphosphate Aldolase