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Protein disulphide‐isomerase is located in the endoplasmic reticulum of developing wheat endosperm
Author(s) -
Roden Linda T.,
Miflin Benjamin J.,
Freedman Robert B.
Publication year - 1982
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(82)80409-2
Subject(s) - freedman , endosperm , endoplasmic reticulum , library science , chemistry , computer science , political science , biochemistry , law
The storage proteins of wheat and other cereals are synthesized during the mid and late phases of seed development and laid down as protein bodies within the endosperm. The nascent proteins are translated on membrane-bound ribosomes and translocated across the endoplasmic reticulum during translation [ 11. Although the proteins are not secreted, but accumulate within the lumen of the endoplasmic reticulum, there appear to be many formal similarities between the post-translational processing of cereal storage proteins and that of secretory proteins in higher animals. The systems are homologous in many respects; in [2] mRNA for zein, the major storage protein of maize, was translated in Xenopus laevis oocytes and deposited within the lumen of the oocyte endoplasmic reticulum. of mammalian tissues active in the biosynthesis and secretion of disulphidebonded proteins [6]. The tissue distribution, sub-cellular distribution, catalytic specificity and developmental properties are all consistent with its participation in the biosynthesis of disulphide-bonded secretory proteins [7,8]. Protein disulphide-isomerase has been detected in mature seeds of wheat, both in the germ and endosperm fractions [9], but its physiological role has not been established. We show that the enzyme is located in the endoplasmic reticulum of developing wheat endosperm, a location consistent with its playing a role in the formation of disulphide bonds during biosynthesis of wheat storage proteins.