The free and membrane-bound ribosomes of hepatic cells were isolated and used to program protein synthesis in cell-free extracts. Immuno-electrophoretic and radioautographic analysis of the products showed that the membrane-bound ribosomes synthesized serum proteins, whereas ribosomes free of endoplasmic reticulum synthesized specific nonserum liver proteins. After synthesis, the serum proteins...

The lateral mobility of ribosomes bound to rough endoplasmic reticulum (RER) membranes was demonstrated under experimental conditions. High-salt-washed rough microsomes were treated with pancreatic ribonuclease (RNase) to cleave the mRNA of bound polyribosomes and allow the movement of individual bound ribosomesmfreeze-etch and thin-section electron microscopy demonstrated that, when rough micr...

Purpose: Osteoarthritis (OA) is characterized by progressive loss and destruction of articular cartilage. Articular chondrocytes produce maintain the cartilage extracellular matrix (ECM), which requires continuous translation mRNAs ribosomes. Recent studies demonstrate that ribosomes can be dynamic heterogeneous. Post-transcriptional modifications (PTMs) ribosomal RNAs (rRNAs), such as 2’-O-rib...

The number of proteins in rat liver ribosomes was determined by two-dimensional polyacrylamide gel electrophoresis. There were 30 proteins in the 40 S subunit, 39 in the 60 S subunit. The proteins of the two subunits, with one possible exception, are unique. Preparations of 80 S ribosomes contained three proteins not present in either subunit; thus, we estimate that eukaryotic ribosomes contain...

Ribosome-inactivating proteins (RIPs) are plant toxins that irreversibly damage ribosomes and other substrates, thus causing cell death. RIPs classified in type 1 RIPs, single-chain enzymatic proteins, 2 consisting of active A chains, similar to linked lectin B which enable the rapid internalization toxin into cell. For this reason, many very cytotoxic, ricin, volkensin stenodactylin being most...

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...

The cotranslational translocation of proteins across the ER membrane involves the tight binding of translating ribosomes to the membrane, presumably to ribosome receptors. The identity of the latter has been controversial. One putative receptor candidate is Sec61 alpha, a multi-spanning membrane protein that is associated with two additional membrane proteins (Sec61 beta and gamma) to form the ...

Ribosomes prepared from somatic tissue of Xenopus laevis inhibit transcription by RNA polymerase III. This observation parallels an earlier report that a high speed fraction from activated egg extract, which is enrichedin ribosomes, inhibits RNA polymerase III activityand destabilizes putative transcription complexes assembled on oocyte 5S rRNA genes. Transcription of somatic- and oocyte-type 5...