Direct visualization of a transmembrane channel associated with ribosomes.
Examination of directly frozen rough endoplasmic reticulum (ER) of retinal pigment epithelial cells by freeze-fracture and freeze-substitution revealed distinct paired transmembrane proteins associated with membrane ribosomes. Ribosomal subunits on intact ER membrane are directly visualized for the first time, providing a global view of the structure of the ribosome and the corresponding structures on the ER membrane. The ribosomal intersubunit cleft appears to be continuous with a cleft between paired transmembrane proteins that extends into the lumen of the ER. This continuous cleft may be the path taken by nascent polypeptides.
Miyaguchi
K
K
Department of Anatomy, Osaka University Medical School, Japan. katsu@codon.nih.gov
Reese
T S
TS
D000818:Animals; D002645:Chickens; D018870:Endoplasmic Reticulum, Rough / Q000648:ultrastructure*; D005614:Freeze Fracturing; D005615:Freezing; D007425:Intracellular Membranes / Q000648:ultrastructure; D008854:Microscopy, Electron / Q000379:methods; D008961:Models, Structural; D010857:Pigment Epithelium of Eye / Q000648:ultrastructure*; D012270:Ribosomes / Q000648:ultrastructure*