Protein biosynthesis in a cell-free system from bovine retina.
A cell-free extract active in the incorporation of [3H]leucine into protein has been prepared from bovine retina. This system may be useful in identifying early precursors and transported forms of the visual  pigment apoprotein. The system completed a minimum of 50% of the preexisting nascent polypeptide chains. 20% of the labelled product accumulated in the soluble fraction of the extract. Gel electrophoresis revealed that this fraction contained six major labelled polypeptide species, each of which correspond to a major unlabelled soluble polypeptide. Some completed polypeptides were retained in the particulate fraction of the extract; several of these were resolved on gel electrophoresis and were of very high specific radioactivity. An antiserum to rod outer segment disc proteins precipitated several labelled species from each fraction. The most interesting of these is a polypeptide of molecular weight 41 000 which was found only in the particulate fraction.
D000818:Animals; D002417:Cattle; D002474:Cell-Free System; D011132:Polyribosomes / Q000378:metabolism; D011233:Precipitin Tests; D014176:Protein Biosynthesis; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D012160:Retina / Q000378:metabolism*