Secretory protein synthesis in Chironomus salivary gland cells is not coupled with protein translocation across endoplasmic reticulum membranes. Electron microscopic evidence.
Fragments of rough endoplasmic reticulum containing polysomes bound to the membranes only at the 5 end were visualized in electron microscopic spreads from Chironomus thummi salivary gland cells. The length of the nascent protein molecules in the polysomes increased from the 5 to the 3 (free) polysome end. The data obtained disagree with the generally accepted model according to which synthesis of secretory proteins is concomitant with the protein transport across the endoplasmic membrane.
Kiseleva
E V
EV
Institute of Cytology and Genetics, Academy of Sciences, USSR Siberian Division, Novosibirsk.
D000818:Animals; D001692:Biological Transport; D002683:Chironomidae; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism; D007814:Larva; D008854:Microscopy, Electron; D011132:Polyribosomes / Q000378:metabolism*; D014176:Protein Biosynthesis; D011506:Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D012469:Salivary Glands / Q000378:metabolism / Q000648:ultrastructure; D012471:Salivary Proteins and Peptides / Q000378:metabolism*
D011506:Proteins; D012333:RNA, Messenger; D012471:Salivary Proteins and Peptides