Limited proteolysis of liver aldolase and fructose 1,6-bisphosphatase by lysosomal proteinases: effect on complex formation

Abstract

Cathepsin M, which catalyzes inactivation of both rabbit liver fructose-1,6-bisphosphate aldolase (EC 4.1.2.13) and rabbit liver fructose 1,6-bisphosphatase (Fru-P2ase; EC 3.1.3.11), has been characterized as a peptidyl peptidase. Modification of the COOH terminus of aldolase by cathepsin M or by Fru-P2ase converting enzyme 2 abolishes its ability to bind to phosphocellulose P11 and to form the complex with Fru-P2ase. On the other hand, modification of the COOH terminus of Fru-P2ase does not affect its interaction with aldolase. This property is lost, however, when Fru-P2ase is modified in the NH2-terminal region by the converting enzyme or by subtilisin. The results suggest that interaction of aldolase and Fru-P2ase may involve the exposed COOH-terminal region of the former and an exposed proteinase-sensitive region located between residues 57 and 67 of the latter.