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Biosynthesis and Secretion of α1-Antitrypsin in Primary Cultures of Rat Hepatocytes.
- Source :
- European Journal of Biochemistry; 12/15/82, Vol. 129 Issue 2, p317-323, 7p
- Publication Year :
- 1982
-
Abstract
- The biosynthesis and secretion of α<subscript>1</subscript>-antitrypsin was studied in rat hepatocyte primary cultures. After labeling with [<superscript>35</superscript>S]methionine an α<subscript>1</subscript>-antitrypsin with an apparent molecular weight of 49000 estimated by sodium dodecyl sulfate polyacrylamide slab gel electrophoresis was immunoprecipitated from the cell homogenate. This intracellular form of α<subscript>1</subscript> -antitrypsin could be deglycosylated by endoglycosidase H treatment indicating that its oligosaccharide chains were of the high-mannose type. Pulse-chase experiments showed that about 30 min after its synthesis the transformation of the 49000-M<subscript>r</subscript> α<subscript>1</subscript> -antitrypsin to a protein with an apparent molecular weight of 54000 began. Only this 54000-M<subscript>r</subscript> protein was secreted by the hepatocytes. The 54000-M<subscript>r</subscript> α<subscript>1</subscript> -antitrypsin was not sensitive to endoglycosidase H, but sensitive to neuraminidase, and it incorporated [³H]galactose and [³H]fucose indicating that its oligosaccharide chains were of the complex type. In the presence of tunicamycin, which blocks the formation of N-asparagine-linked oligosaccharide chains, an unglycosylated α<subscript>1</subscript>-antitrypsin with an apparent molecular weight of 41000 was found in the cells as well as in the medium. However, tunicamycin decreased the secretion of α<subscript>1</subscript>-antitrypsin by 60–70%, whereas the secretion of albumin remained unaffected. In the presence of colchicine the secretion of both α<subscript>1</subscript>-antitrypsin and albumin was impaired. The results demonstrate the importance of glycosylation for the secretion of α<subscript>1</subscript>-antitrypsin. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00142956
- Volume :
- 129
- Issue :
- 2
- Database :
- Complementary Index
- Journal :
- European Journal of Biochemistry
- Publication Type :
- Academic Journal
- Accession number :
- 15803758
- Full Text :
- https://doi.org/10.1111/j.1432-1033.1982.tb07054.x