Role ofO-Linked Carbohydrate of Human Urinary Trypsin Inhibitor on Its Lysosomal Membrane-Stabilizing Property

• Published in: Biochemical and biophysical research communications Vol. 243; no. 2; pp. 377 - 383
• Main Authors: Kato, Y., Kudo, M., Shinkawa, T., Mochizuki, H., Isaji, M., Shiromizu, I., Hoshida, K.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01-02-1998
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.1998.8100

Human urinary trypsin inhibitor (UTI) was digested with various enzymes to obtainO-glycoside linked N-terminal glycopeptide (UTIm1),N-glycoside linked C-terminal tandem Kunitz-domains (domain I and II, UTIm2), UTI lackingO-glycoside (UTIc), asialo UTI (UTIa) and UTI lacking N-glycoside (UTIn). We investigated the membrane stabilizing effect of these UTI derivatives on rat renal lysosome by measurement of lysosomal enzymeN-acetyl-β-D-glucosaminidase (NAG) release after hypotonic treatment. Intact UTI suppressed NAG release, but aprotinin, gabexate mesilate (FOY), nafamostat mesilate (FUT) and recombinant domain II of UTI (R-020) had no effect, indicating that inhibition of serine proteases was not involved and the carbohydrate moiety of UTI might be necessary for this property. Among UTI derivatives, UTIm1, UTIm2, UTIm1+ UTIm2, and UTIc had no effect. In contrast, UTIa or UTIn suppressed NAG release. From these results, we conclude thatO-glycoside linked core protein withoutN-glycoside is essential to the lysosomal membrane-stabilizing property of UTI.