TY - JOUR
T1 - Lysosomal cysteine protease, cathepsin H, is targeted to lysosomes by the mannose 6-phosphate-independent system in rat hepatocytes
AU - Tanaka, Yoshitaka
AU - Tanaka, Rie
AU - Himeno, Masaru
N1 - Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2000/7
Y1 - 2000/7
N2 - The contribution of mannose 6-phosphate (Man 6-P)-dependent and - independent systems to lysosomal targeting of cathepsin H, a lysosomal cysteine protease, was investigated by metabolic labeling with [32P]phosphate and [35S]methionine/cysteine in primary cultures of rat hepatocytes. Metabolic labeling experiments with [32P]phosphate revealed that only the proform of cathepsin H acquired Man 6-P residues on its high mannose type oligosaccharide, and that most of the phosphorylated procathepsin H was secreted into the medium without having undergone significant intracellular dephosphorylation. Thus, acquisition of Man 6-P residues did not correlate with targeting of cathepsin H to lysosomes. Pulse- chase experiments with [35S]methionine/cysteine showed that only about 10% of the newly synthesized cathepsin H was secreted as a proform while the remainder was retained intracellularly in processed mature form. These results indicate that the majority of newly synthesized cathepsin H is targeted to lysosomes by a Man 6-P-independent mechanism, at least in rat hepatocytes.
AB - The contribution of mannose 6-phosphate (Man 6-P)-dependent and - independent systems to lysosomal targeting of cathepsin H, a lysosomal cysteine protease, was investigated by metabolic labeling with [32P]phosphate and [35S]methionine/cysteine in primary cultures of rat hepatocytes. Metabolic labeling experiments with [32P]phosphate revealed that only the proform of cathepsin H acquired Man 6-P residues on its high mannose type oligosaccharide, and that most of the phosphorylated procathepsin H was secreted into the medium without having undergone significant intracellular dephosphorylation. Thus, acquisition of Man 6-P residues did not correlate with targeting of cathepsin H to lysosomes. Pulse- chase experiments with [35S]methionine/cysteine showed that only about 10% of the newly synthesized cathepsin H was secreted as a proform while the remainder was retained intracellularly in processed mature form. These results indicate that the majority of newly synthesized cathepsin H is targeted to lysosomes by a Man 6-P-independent mechanism, at least in rat hepatocytes.
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U2 - 10.1248/bpb.23.805
DO - 10.1248/bpb.23.805
M3 - Article
C2 - 10919356
AN - SCOPUS:0033931161
VL - 23
SP - 805
EP - 809
JO - Biological and Pharmaceutical Bulletin
JF - Biological and Pharmaceutical Bulletin
SN - 0918-6158
IS - 7
ER -