Processing in vitro of placental peptide hormones by smooth microsomes.
Rough and smooth microsomes were prepared from ascites tumor cells, rat liver, and bovine adrenal cortex. Proteolytic removal of the signal peptide in pre-placental lactogen and asparagine-linked glycosylation of the alpha subunit of chorionic gonadotropin by these fractions were examined in mRNA-dependent lysates from ascites cells. Both processing steps were performed by smooth microsomes, which was unexpected because it has been presumed that only rough microsomes contain components for ribosomal binding. Thus smooth microsomes are apparently capable of interacting with polysomes bearing secretory nascent chains, and cleavage and asparagine-linked glycosylation activities are present in both rough and smooth endoplasmic reticulum.
D000302:Adrenal Cortex / Q000648:ultrastructure; D000818:Animals; D001201:Ascites / Q000473:pathology; D002417:Cattle; D006063:Chorionic Gonadotropin / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism*; D006602:Hexosyltransferases / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism*; D008862:Microsomes, Liver / Q000378:metabolism; D008970:Molecular Weight; D009374:Neoplasms, Experimental / Q000648:ultrastructure; D010928:Placental Lactogen / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D051381:Rats
D006063:Chorionic Gonadotropin; D006023:Glycoproteins; D008565:Membrane Proteins; D011498:Protein Precursors; D010928:Placental Lactogen; D006602:Hexosyltransferases