This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Adeli, K. Articles by Altosaar, I. Search for Related Content PubMed PubMed Citation Articles by Adeli, K. Articles by Altosaar, I. Agricola Articles by Adeli, K. Articles by Altosaar, I.

Articles

Role of Endoplasmic Reticulum in Biosynthesis of Oat Globulin Precursors ¹

Department of Biochemistry, University of Ottawa, Ottawa, Ontario, Canada K1N 9B4

Oat (Avena sativa L.) groats were labeled with radioactive leucine and salt-soluble proteins were extracted and analyzed. Polyacrylamide gel electrophoresis followed by fluorography indicated two radioactive polypeptides with molecular weight 58 to 62 kilodaltons which were similar in size to unreduced globulin - dimers. The role of endoplasmic reticulum in the synthesis of these globulin polypeptides was investigated by in vivo and in vitro protein synthesis studies. Labeled tissue was fractionated by centrifugation and rough endoplasmic reticulum was isolated. Two polypeptides which had molecular weights of 58 to 62 kilodaltons and were immunoprecipitable with antiglobulin immunoglobulin G were found to be transiently associated with the endoplasmic reticulum. Rough endoplasmic reticulum, as well as membrane-bound polysomes, directed the in vitro synthesis of two polypeptides with molecular weight 58 to 62 kilodaltons corresponding in size to unreduced - dimers and could be immunoprecipitated with antiglobulin immunoglobulin G. The translation products of free polysomes did not show this. In pulse-labeling, globulin polypeptides with molecular weight 58 to 62 kilodaltons, as well as the + subunits, were labeled in protein bodies.

The data suggest that oat globulin polypeptides are synthesized as higher molecular weight precursors on ER-associated polysomes. These precursors are probably transported into protein bodies and cleaved into smaller and subunits.