[Carbohydrate phosphotransferase in human hepatoma and phosphorylation of cathepsin D].

Abstract

Two enzymes (N-acetylglucosamine-1-phosphotransferase and phosphodiester glycosidase) involved in formation of mannose-6-phosphate at lysosomal hydrolases were studied for the activity and kinetics in human hepatocellular carcinoma. The activity level of the phosphotransferase with an artificial substrate was elevated (p less than 0.025) in hepatoma compared to that in normal liver, while the phosphodiester glycosidase of hepatoma was in a similar level with that of control. The elevation was more remarkable with a physiological substrate, cathepsin D. (P less than 0.001). Since cathepsin D from normal liver was previously demonstrated to contain less phosphomannose compared to the hepatoma protease, the protease was investigated for carbohydrate phosphorylation by the phosphotransferase. The liver protease was much more phosphorylated than the hepatoma protease, endorsing the previous observation. The predominant phosphorylation of the protease occurred in heavy subunit.

• Authors: M Ohhira
• Journal: [Hokkaido igaku zasshi] The Hokkaido journal of medical science (Hokkaido Igaku Zasshi) Vol. 65 Issue 6 Pg. 560-7 (Nov 1990) ISSN: 0367-6102 [Print] Japan
• PMID: 2176173 (Publication Type: English Abstract, Journal Article)

Chemical References

• Mannosephosphates
• Phosphotransferases
• Cathepsin D

Topics

• Carcinoma, Hepatocellular (enzymology)
• Cathepsin D (metabolism)
• Humans
• Liver Neoplasms (enzymology)
• Mannosephosphates
• Phosphorylation
• Phosphotransferases (metabolism)
• Protein Processing, Post-Translational