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Haptoglobin. A novel mode of biosynthesis of a liver secretory glycoprotein
Journal article   Open access   Peer reviewed

Haptoglobin. A novel mode of biosynthesis of a liver secretory glycoprotein

Thomas H Haugen, Joan M Hanley and Edward C Heath
The Journal of biological chemistry, Vol.256(3), pp.1055-1057
02/10/1981
DOI: 10.1016/S0021-9258(19)69917-5
PMID: 7451486
url
https://doi.org/10.1016/S0021-9258(19)69917-5View
Published (Version of record) Open Access

Abstract

The de novo biosynthesis of the heterotetrameric (alpha 2 beta 2) serum glycoprotein, haptoglobin, was studied using a rabbit reticulocyte cell-free translation system and mRNA preparations from the livers of turpentine-treated rats. Analysis of the translation mixtures with either antisera specific for the alpha-subunit (anti-alpha-IgG) or the beta-subunit (anti-beta-IgG) or the native haptoglobin tetramer (anti-alpha 2 beta 2-IgG) resulted in each instance in the recovery of a single protein exhibiting a Mr = approximately 38,000. Cleavage of the translation product with cyanogen bromide or trypsin resulted in the generation of small peptide fragments that were specifically immunoadsorbed with either anti-alpha-IgG or anti-beta-IgG. These results indicated that the primary translation product of haptoglobin mRNA is a single polypeptide that contains the elements of both the alpha-subunit and the beta-subunit of the protein. Presumably haptoglobin is synthesized in vitro as a single precursor protein that is proteolytically processed post-translationally to form the dissimilar alpha- and beta-subunits of the native protein.
Inflammation Rabbits Protein Biosynthesis Animals Haptoglobins - biosynthesis Molecular Weight Cell-Free System Liver - metabolism Rats RNA, Messenger - metabolism Reticulocytes - metabolism Macromolecular Substances

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