Open AccessSynthesis and secretion of hemopexin in primary cultures of rat hepatocyts
Author(s) -
KATZ Norbert R.,
GOLDFARB Valentina,
LIEM Heng,
MULLEREBERHARD Ursula
Publication year - 1985
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1985.tb08632.x
Subject(s) - hemopexin , secretion , transferrin , glycosylation , intracellular , biochemistry , chemistry , tunicamycin , microbiology and biotechnology , biology , endoplasmic reticulum , enzyme , heme , unfolded protein response
Secretion of hemopexin (20% carbohydrate) and its dependence on glycosylation was studied in primary rat hepatocyte cultures in comparison to the secretion of transferrin (5% carbohydrate).1 In pulse‐chase experiments with [ 35 S]methionine half of the labeled hemopexin was secreted in 30 min. By contrast, it took approximately 50 min for secretion of half of the transferrin. 2 Tunicamycin treatment of cultures significantly delayed the secretion of hemopexin but not that of transferrin. 3 During the pulse period a proiod a prominent intracellular precursor of hemopexin, smaller than the mature protein, was evident.It is concluded that the extent of glycosylation of a secretory protein is not necessarily a determinant of the transit time required for intracellular processing and secretion. In the case of hemopexin the glycosylation apparently facilitates the secretion although it is not an absolute prerequisite for the exocytosis of this protein.