Maturation and degradation of beta-galactosidase in the post-Golgi compartment are regulated by cathepsin B and a non-cysteine protease.
Lysosomal beta-galactosidase precursor is processed to a mature form and associated with protective protein in lysosomes. In this study we used two cysteine protease proinhibitors, E64-d for cathepsins B, S, H, and L, and CA074Me for cathepsin B. They are converted intracellularly to active forms, E-64c and CA074, respectively. Both active compounds inhibited maturation of the exogenous beta-galactosidase precursor, but E-64c did not inhibit further degradation to an inactive 50-kDa product. We concluded that cathepsin B participated exclusively in maturation of beta-galactosidase, and a non-cysteine protease was involved in further degradation and inactivation of the enzyme molecule.
Okamura-Oho
Y
Y
Department of Clinical Genetics, The Tokyo Metropolitan Institute of Medical Science, Japan.
Zhang
S
S
Callahan
J W
JW
Murata
M
M
Oshima
A
A
Suzuki
Y
Y
D002401:Cathepsin B / Q000378:metabolism*; D002451:Cell Compartmentation; D002460:Cell Line; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D008247:Lysosomes / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism*
D015853:Cysteine Proteinase Inhibitors; D001616:beta-Galactosidase; D002401:Cathepsin B