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Pulse-chase Analysis of N-linked Sugar Chains from Glycoproteins in Mammalian Cells
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Pulse-chase Analysis of N-linked Sugar Chains from Glycoproteins in Mammalian Cells

Published on: April 27, 2010

Distribution of protein-bound sugar residues in microsomal subfractions and Golgi membranes

A Bergman, G Dallner

    Biochimica Et Biophysica Acta
    |May 21, 1976
    PubMed

    Insights

    This study reveals distinct sugar compositions in liver cell membranes, with varying mannose-galactose ratios across microsomes and Golgi. Detergent and enzyme treatments further differentiate these membrane sugar components.

    Area of Science:

    • Biochemistry
    • Cell Biology
    • Glycobiology

    Background:

    • Liver microsomes and Golgi membranes contain characteristic sugar compositions.
    • These membrane fractions are involved in protein synthesis and modification.

    Purpose of the Study:

    • To characterize the sugar composition of liver microsomal subfractions and Golgi membranes.
    • To investigate the distribution and accessibility of specific sugars within these cellular structures.

    Main Methods:

    • Analysis of sugar composition (mannose, galactose, glucosamine, sialic acid) in isolated liver microsomes and Golgi membranes.
    • Treatment with deoxycholate to assess detergent-sensitive sugars.
    • Enzymatic digestion with trypsin to determine the accessibility of sugars on the vesicle surface and interior.

    Main Results:

    • A gradient in the mannose to galactose ratio was observed, decreasing from rough microsomes to Golgi membranes.
    • Glucosamine and sialic acid levels varied, with higher concentrations in smooth microsomes and Golgi membranes.
    • Deoxycholate preferentially removed protein-bound mannose and glucosamine.
    • Trypsin treatment released surface-exposed mannose and galactose, with additional mannose released from permeable vesicles.

    Conclusions:

    • Liver microsomal and Golgi membranes exhibit distinct and characteristic sugar profiles.
    • The accessibility of sugars to enzymatic and chemical treatments provides insights into their localization within these membrane structures.
    • These findings contribute to understanding the structural organization and function of liver cell membranes.

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