文章基本信息

标题：Lysosomal Cysteine Protease, Cathepsin H, Is Targeted to Lysosomes by the Mannose 6-Phosphate-Independent System in Rat Hepatocytes
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作者：Yoshitaka TANAKA ; Rie TANAKA ; Masaru HIMENO 等
期刊名称：Biological and Pharmaceutical Bulletin
印刷版ISSN：0918-6158
电子版ISSN：1347-5215
出版年度：2000
卷号：23
期号：7
页码：805-809
DOI：10.1248/bpb.23.805
出版社：The Pharmaceutical Society of Japan
摘要：The contribution of mannose 6-phosphate (Man 6-P)-dependent and -independent systems to lysosomal targeting of cathepsin H, a lysosomal cysteine 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 oligosacchardie, 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 a 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.
关键词：cathepsin H;hepatocyte;mannose 6-phosphate;lysosome;protein sorting