Eukaryotic mRNA is processed by enzymes and packaged with proteins within nuclei to generate functional messenger ribonucleoprotein (mRNP) particles. Processing and packaging factors can interact with mRNA cotranscriptionally to form an early mRNP. Erroneous mRNP formation leads to nuclear retention and degradation of the mRNA. It therefore appears that one function of cotranscriptional mRNP as...

The stable ribonucleoprotein (RNP) complex formed between the Lactococcus lactis group II intron and its self-encoded LtrA protein is essential for the intron's genetic mobility. In this study, we report the biochemical, compositional, hydrodynamic and structural properties of active group II intron RNP particles (+A) isolated from its native host using a novel purification scheme. We employed ...

Coronavirus particles are enveloped and pleomorphic and are thus refractory to crystallization and symmetry-assisted reconstruction. A novel methodology of single-particle image analysis was applied to selected virus features to obtain a detailed model of the oligomeric state and spatial relationships among viral structural proteins. Two-dimensional images of the S, M, and N structural proteins...

Three monoclonal antibodies elicited to NIH 3T3 cells transfected with DNA from a human pancreatic adenocarcinoma cell line recognized a novel ribonucleoprotein complex. Minimally, this ribonucleoprotein complex contained a M, 240,000 protein (by sodium dodecyl sulfatepolyacrylamide gel electrophoresis) and two RNA species with apparent sizes of 1.5 and 3.0 kilobases (by formaldehyde agarose ge...

A specific, 0.1-0.3-microm large ribonucleoprotein complex consisting of a central core with stalklike extensions on top of which 280-320-A ribonucleoprotein particles are situated is found in an experimentally activated chromosome region, 2-48C, of the polytene chromosomes of Drosophila hydei. Alkaline hydrolysis, RNAse digestion, and uranyl-EDTA-lead staining indicated the ribonucleoprotein c...

Sypherd, Paul S. (University of California, San Diego). Formation of ribosomes from precursor ribonucleoprotein particles. J. Bacteriol. 90:411-417. 1965.-Amino acid deprivation of a "relaxed" mutant leads to the accumulation of ribonucleoprotein particles. The possibility that these particles are equivalent to normal ribosome precursors was investigated. This was accomplished by determining th...

The ribonucleoprotein complex ribonuclease (RNase) MRP is a site-specific endoribonuclease essential for the survival of the eukaryotic cell. RNase MRP closely resembles RNase P (a universal endoribonuclease responsible for the maturation of the 5' ends of tRNA) but recognizes distinct substrates including pre-rRNA and mRNA. Here we report the results of an in vitro selection of Saccharomyces c...