Nascent Ribosomes
نویسنده
چکیده
The conversion of a ribosomal RNA transcript to a cytoplasmic ribosome requires hundreds of accessory RNA and protein factors. Two papers published recently in Molecular Cell provide first looks at the association of these processing factors with the intermediates in ribosome synthesis (Harnpicharnchai et al., 2001; Bassler et al., 2001).
منابع مشابه
Evidence for Synthesis of Proteins of Chloroplastic Ribosomes Ox Cytoplasmic Ri- Bosomes*
The biosynthesis of proteins of chloroplastic (67 S) and cytoplasmic (83 S) ribosomes of Chlamydomonas reinhardi was studied in viva using both wild type and the arginine auxotroph, arg-1. The incorporation of amino acids into nascent protein (chaseable label) and ribosomal structural protein (nonchaseable label) was examined. When cells of tug-1 were incubated with excess radioactive arginine,...
متن کاملIdentification of a Novel Stage of Ribosome/Nascent Chain Association with the Endoplasmic Reticulum Membrane
Protein translocation in the mammalian endoplasmic reticulum (ER) occurs cotranslationally and requires the binding of translationally active ribosomes to components of the ER membrane. Three candidate ribosome receptors, p180, p34, and Sec61p, have been identified in binding studies with inactive ribosomes, suggesting that ribosome binding is mediated through a receptor-ligand interaction. To ...
متن کاملNascent polypeptide-associated complex protein prevents mistargeting of nascent chains to the endoplasmic reticulum.
We show that, after removal of the nascent polypeptide-associated complex (NAC) from ribosome-associated nascent chains, ribosomes synthesizing proteins lacking signal peptides are efficiently targeted to the endoplasmic reticulum (ER) membrane. After this mistargeting, translocation across the ER membrane occurs, albeit less efficiently than for a nascent secretory polypeptide, perhaps because...
متن کاملProtein synthesis by membrane-bound and free ribosomes of secretory and non-secretory tissues.
1. Methods for the separation of membrane-bound and free ribosomes from rat brain (cortex) and skeletal muscle were described and the preparations characterized by chemical analysis and electron microscopy. The attachment of ribosomes to membranes is not an artifact of the separation procedure. 2. The rate of incorporation of l-[(14)C]leucine into protein in vitro by the membrane-bound and free...
متن کاملThe molecular chaperone Ssb from Saccharomyces cerevisiae is a component of the ribosome-nascent chain complex.
The 70 kDa heat shock proteins (Hsp70s) are a ubiquitous class of molecular chaperones. The Ssbs of Saccharomyces cerevisiae are an abundant type of Hsp70 found associated with translating ribosomes. To understand better the function of Ssb in association with ribosomes, the Ssb-ribosome interaction was characterized. Incorporation of the aminoacyl-tRNA analog puromycin by translating ribosomes...
متن کاملCONTROLLED PROTEOLYSIS OF NASCENT POLYPEPTIDES IN RAT LIVER CELL FRACTIONS II. Location of the Polypeptides in Rough Microsomes
Rough microsomes were incubated in an in vitro amino acid-incorporating system for labeling the nascent polypeptide chains on the membrane-bound ribosomes . Sucrose density gradient analysis showed that ribosomes did not detach from the membranes during incorporation in vitro. Trypsin and chymotrypsin treatment of microsomes at 0 ° led to the detachment of ribosomes from the membranes ; further...
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عنوان ژورنال:
- Cell
دوره 107 شماره
صفحات -
تاریخ انتشار 2001