These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Functional characterization of the N-glycosylation sites of human acid sphingomyelinase by site-directed mutagenesis.
    Author: Ferlinz K, Hurwitz R, Moczall H, Lansmann S, Schuchman EH, Sandhoff K.
    Journal: Eur J Biochem; 1997 Jan 15; 243(1-2):511-7. PubMed ID: 9030779.
    Abstract:
    Most soluble lysosomal enzymes require a mannose-6-phosphate recognition marker present on asparagine-linked oligosaccharides for proper targeting to lysosomes. We have determined the influence of the six potential N-linked oligosaccharide chains of human acid sphingomyelinase (ASM) on catalytic activity, targeting, and processing of the enzyme. Each N-glycosylation site was modified by site-directed mutagenesis and subsequently expressed in COS-1 cells. Evidence is presented that five of these sites are used. Elimination of the four N-terminal glycosylation sites does not disturb lysosomal targeting, processing, or enzymatic activity. However, removal of the two C-terminal N-glycosylation sites inhibits the formation of mature enzyme. Absence of glycosylation site five resulted in rapid cleavage of the primary translation product to an enzymatically inactive protein which accumulated inside the endoplasmic reticulum/Golgi, whereas deletion of glycosylation site six led to the formation of an inactive ASM precursor, also retained inside the endoplasmic reticulum/Golgi. Our results also provide evidence that the site of early proteolytic cleavage of newly synthesized ASM must be located between the second and third glycosylation sites.
    [Abstract] [Full Text] [Related] [New Search]