title: Regulation of polysome assembly on the endoplasmic reticulum by a coiled-coil protein, p180.
abstract: A coiled-coil microtubule-bundling protein, p180, was originally identified as one of the ribosome receptor candidates on the rough endoplasmic reticulum (ER) and is highly expressed in secretory tissues. Recently, we reported that p180 plays crucial roles in upregulating collagen biosynthesis, mainly by facilitating ribosome association on the ER. Here, we provide evidence that p180 is required to form translationally active polysome/translocon complexes on the ER. Assembly of highly-developed polysomes on the ER was severely perturbed upon loss of p180. p180 associates with polysome/translocon complexes through multiple contact sites: it was coimmunoprecipitated with the translocon complex independently of ribosomes, while it can also bind to ribosomal large subunit specifically. The responsible domain of p180 for membrane polysome assembly was identified in the C-terminal coiled-coil region. The degree of ribosome occupation of collagen and fibronectin mRNAs was regulated in response to increased traffic demands. This effect appears to be exerted in a manner specific for a specified set of mRNAs. Collectively, our data suggest that p180 is required to form translationally active polysome/translocon complexes on the ER membrane, and plays a pivotal role in highly efficient biosynthesis on the ER membrane through facilitating polysome formation in professional secretory cells.
authors.affiliation: Nippi Research Institute of Biomatrix, Toride, Ibaraki 302-0017, Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Ueno
authors.forename: Keiko
authors.initials: K
authors.lastname: Kaneko
authors.forename: Tetsutaro
authors.initials: T
authors.lastname: Sata
authors.forename: Shunji
authors.initials: S
authors.lastname: Hattori
authors.forename: Kiyoko
authors.initials: K
authors.lastname: Ogawa-Goto
mesh_terms: D001205:Ascorbic Acid / Q000494:pharmacology; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism* / Q000648:ultrastructure; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D011132:Polyribosomes / Q000378:metabolism* / Q000648:ultrastructure; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism; D002352:Carrier Proteins
chemical_list: D001205:Ascorbic Acid; D003094:Collagen; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; C000602809:RRBP1 protein, human; D002352:Carrier Proteins