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At least 37 records · Page 2Linked to original sources
PubMed1975

Specific cleavage of Sendai virus nucleocapsid protein subunits during virus storage.

The alteration of whole Sendai virus and especially of its nucleocapsid polypeptides, during storage of the virus at 4 degree C in the allantoic fluids in which it was cultivated, has cultivated, has been studied by sodium dodecyl sulfate gel electrophoresis. During virus storage the nucleocapsid protein subunits with a molecular weight of 60,000 and the putative inner envelope protein with a molecular weight of 38,000 were mainly affected. Both virus components were partially degraded to smaller components. Examination of nucleocapsids isolated from "stored" virus showed that, in addition to the 60,000-molecular weight polypetide component, a smaller polypeptide component with a molecular weight of 46,000 appeared. The relative proportion of the small component increased with the storage period: a kind of specific conversion of large to small components occurred during storage. Since viruses kept in the absence of allantoic fluids revealed no similar modifications of their polypeptides, we concluded that a cellular component present in the allantoic fluids - very likely of enzymatic nature - is responsible for the observed cleavage of virus polypeptides.

Body Fluids↗
PubMed1979

Large-scale purification of Na,K-ATPase and its protein subunits from lamb kidney medulla.

Procedures are described for the large-scale isolation of purified Na,K-ATPase (EC 3.6.1.3) from frozen lamb kidney outer medulla and for the separation of its two protein subunits by hydroxyapatite chromatography in sodium dodecyl sulfate (SDS). The methods described permit the routine isolation of up to 800 mg of purified Na,K-ATPase in one week, which can subsequently be separated into 500 mg of mr = 95,000 catalytic subunit and 200 mg of glycoprotein with four SDS-hydroxyapatite column runs.

Animals↗
PubMed1975

RNA-protein interactions in the ribosome. Binding of 50-S-subunit proteins to 5' and 3' terminal segments of the 23-S RNA.

Limited digestion of the Escherichia coli 50-S subunit permits the isolation of two large fragments of the 23-S RNA. One arises from the 5' end of the 23-S RNA and contains about 1200 nucleotides. The other arises from the 3' end of the 23-S RNA and contains about 2000 nucleotides. Each of the ten 50-S proteins known to bind specifically and independently to the 23-S RNA were tested for their ability to interact with these two RNA fragments. It was determined that the 5' terminal segment contains the specific binding sites for proteins L4, L20 and L24, whereas the 3' terminal segment contains the specific binding sites for proteins L1, L2, L3, L6, L13, L13 and L23.

Base Sequence↗
PubMed1978

Studies on proteins of animal ribosomes. XXVIII. Preparation and antigenic properties of 40 S subunit proteins of rat liver ribosomes.

By combination of ion exchange chromatography, gel filtration, preparative polyacrylamide gel electrophoresis and perchloric acid fractionation 21 proteins of the small ribosomal subunit of rat liver were isolated with a purity of more than 95%. It could be demonstrated by immunological studies that no extensive structural homologies exist between these proteins.

Animals↗
PubMed1979

Influence of magnesium and polyamines on the reactivity of individual ribosomal subunit proteins to lactoperoxidase-catalyzed iodination.

30S and 50S subunits, in the presence of either 20 mM Mg2+ or 6 mM Mg2+ and 5mM spermidine plus 25 mM putrescine, were observed to completely associate to form 70S monosomes as monitored by sucrose gradient sedimentation. Subunits maintained under the above ionic conditions were compared with 30S and 50S particles at low (6 mM) magnesium concentration with respect to the reactivity of individual ribosomal proteins to lactoperoxidase-catalyzed iodination. Altered reactivity to enzymatic iodination of ribosomal proteins S4, S9, S10, S14, S17, S19, and S20 in the small subunit of ribosomal proteins, L2, L9, L11, L27, and L30 in the large subunit following incubation with high magnesium or magnesium and polyamines suggests that a conformation change in both subunits accompanies the formation of 70S monosomes. The results further demonstrate that the effect of Mg2+ on subunit conformation is mimicked when polyamines are substituted for magnesium necessary for subunit association.

Iodoproteins↗
PubMed1978

Physicochemical and immunological homogeneity of spinin, the subunit-protein of bacterial spinae.

Bacterial spinae from marine bacterium D71 are multi-subunit structures of a single protein. This protein, called spinin, is homogeneous by immunodiffusion and immunoelectrophoresis, amino acid composition, polyacrylamide gel electrophoresis with a number of buffer systems, sedimentation velocity and diffusion boundary analysis. Sedimentation equilibrium gives Mr = 19,000, while phosphate polyacryl-amide gel electrophoresis in presence of dodecyl sulfate gives Mr = 32,000. The lower Mr estimate for spinin is supported by sedimentation equilibrium in 6 M guanidine . HCl, and covalent cross-linking with dimethyl suberimidate or glutaraldehyde. The higher Mr value probably arises from an anomalous spinin-dodecyl sulfate interaction. Isoelectric focusing in polyacrylamide gel gives pI = 3.45; however, the focusing pattern also contains three distinct bands that may arise from hydrolysis of the spinin protomer during anodic migration. This study presents the first extensive physicochemical characterization of spinin and provides the basis for investigating the subunit assembly of spinae.

Amino Acids↗
PubMed1979

Emetine resistance in Chinese hamster cells is linked genetically with an altered 40S ribosomal subunit protein, S20.

Emr-2 is an emetine-resistant (Emr) Chinese hamster ovary cell mutant that contains a single electrophoretically altered ribosomal protein, a component of its 40S ribosomal subunit [Boersma, D., McGill, S., Mollenkamp, J. & Roufa, D.J. (1979) J. Biol. Chem. 254, in press]. This report describes a genetic experiment designed to test linkage between the genes that specify the altered ribosomal protein, S20*, and emetine resistance in Emr clones that segregated from cultures of Emr-2 cells hybridized with emetine-sensitive cells. The data described indicate that Emr and S20* phenotypes are due to mutations linked to the same chromosome in the Chinese hamster genome; most likely they are due to the same mutation. The data also confirm earlier speculations by others that the Emr locus in Chinese hamster cells is hemizygous.

Animals↗
PubMed1977

Progesterone-binding components of chick oviduct. Receptor B subunit protein purified to apparent homogeneity from laying hen oviducts.

The progesterone receptor B subunit has been purified to apparent homogeneity from hen oviduct cytosol using ammonium sulfate precipitation and chromatography on DEAE-cellulose, phosphocellulose, hydroxylapatite, and gel filtration on Agarose A-1.5m. The material is obtained (1 mug of purified protein/g of tissue) in about 17% yield. The protein is highly purified; a single band is seen on gel electrophoresis in acid-urea and sodium dodecyl sulfate gels as well as gel electrophoresis under nondenaturing conditions. In the latter system, labeled progesterone co-migrates with the protein band, demonstrating that the isolated protein is a progesterone-binding species. Labeled progesterone bound to the protein is displaced by progestational steroids but not by estradiol or hydrocortisone. The protein has a molecular weight of 116,000 g/mol as determined by gel electrophoresis and has a single polypeptide chain. The isolated protein contains 98% endogenous nonradioactive progesterone and is 2% labeled by incubation in vitro with radiolabeled progesterone. It behaves identically on all of the chromatographic steps to chick receptor B subunits described in earlier publications.

Animals↗
PubMed1978

Conformational changes in 16S ribosomal RNA induced by 30S ribosomal subunit proteins from Escherichia coli.

Laser light scattering has been used to evaluate conformational differences between free 16S RNA and several specific protein-16S RNA complexes. Proteins that interact strongly with the 16S RNA early in subunit assembly stabilize the RNA chain against unfolding in 1 mM Mg2+ and actually promote the formation of a more compact teriary structure in 20 mM Mg2+. A vital function of these proteins may therfore consist in altering the configuration of the RNA so that further assembly reactions can take place.

Bacterial Proteins↗
PubMed1977

Oligomycin-dependent ionophoric protein subunit of mitochondrial adenosinetriphosphatase.

A proteolipid isolated from yeast mitochondrial adenosinetriphosphatase (subunit 9) (ATP phosphohydrolase; EC 3.6.1.3) by chloroform/methanol extraction has been shown to discharge photo-induced potentials across a planar phospholipid membrane containing bacteriorhodopsin. Oligomycin, a specific inhibitor of oxidative phosphorylation which binds to this protein, allows the potential gradient to be reestablished. When proteolipid was isolated from an oligomycin-resistant strain, ionophoric activity was still obtained but the effect was not reversed by oligomycin. These studies suggest that the hydrophobic subunit-9 polypeptide is the ionophoric component linking ATP synthesis (hydrolysis) with proton translocation.

Adenosine Triphosphatases↗