Messenger RNA for the 73,000-dalton poly(A)-binding protein occurs as translationally repressed mRNP in duck reticulocytes.
Poly(A)-containing mRNA has been prepared from the polyribosomes and post-polyribosomal mRNP fraction of duck reticulocytes. The coding capacity of the respective mRNA populations has been examined by translation in vitro followed by two-dimensional electrophoresis of the 35S-labeled polypeptides. A detailed analysis of these results is given elsewhere (Imaizumi-Scherrer, M.-T., Maundrell, K., Civelli, O., and Scherrer, K. (1982) Dev. Biol. 93, 126-138). Here, we focus on one of these translation products which migrates as a slightly basic protein of 73,000 molecular weight. By two-dimensional electrophoretic analysis and partial peptide mapping, we show that this protein is indistinguishable from the poly(A)-binding protein. We conclude that the majority of the coding sequences for this protein are translationally repressed in the reticulocyte cytoplasm.
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics* / Q000302:isolation & purification; D004372:Ducks; D004591:Electrophoresis, Polyacrylamide Gel; D008970:Molecular Weight; D009698:Nucleoproteins / Q000235:genetics*; D039102:Poly(A)-Binding Proteins; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics*; D012156:Reticulocytes / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000235:genetics*
D002352:Carrier Proteins; D009698:Nucleoproteins; D039102:Poly(A)-Binding Proteins; D012333:RNA, Messenger; D012261:Ribonucleoproteins; C026452:messenger ribonucleoprotein