title: Direct visualization of a transmembrane channel associated with ribosomes.
abstract: 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.
authors.affiliation: Department of Anatomy, Osaka University Medical School, Japan. katsu@codon.nih.gov
authors.forename: K
authors.initials: K
authors.lastname: Miyaguchi
authors.forename: T S
authors.initials: TS
authors.lastname: Reese
mesh_terms: 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*