Journal ArticleDOI
A comparison of ribosomal proteins from rabbit reticulocytes phosphorylated in situ and in vitro.
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A comparison has been made between the ribosomal proteins phosphorylated in intact cells and proteins isolated from Ribosomal subunits after modification in vitro by purified protein kinases and [gamma-32P]ATP.Abstract:
A comparison has been made between the ribosomal proteins phosphorylated in intact cells and proteins isolated from ribosomal subunits after modification in vitro by purified protein kinases and [gamma-32P]ATP. When intact reticulocytes were incubated for 2 h in a nutritional medium containing radioactive inorganic phosphate, one phosphorylated protein was identified as a 40S ribosomal component using two-dimensional polyacrylamide gel electrophoresis followed by electrophoresis in a third step containing sodium dodecyl sulfate. This protein, containing 99% of the total radioactivity associated with ribosomal proteins as observed by two-dimensional electrophoresis, is found in a nonphosphorylated form in addition to several phosphorylated states. These states differ by the number of phosphoryl group attached to the protein. The same 40S protein is modified in vitro by the three cAMP-regulated protein kinases from rabbit reticulocytes. Two additional proteins associated with the 40S subunit are phosphorylated in situ. These proteins migrate as a symmetrical doublet, and contain less than 1% of the radioactive phosphate in the 40S subunit. A number of phosphorylated proteins associated with 60S subunits are observed by disc gel electrophoresis after incubation of whole cells with labeled phosphate. These proteins do not migrate with previously identified ribosomal proteins and are not present in sufficient amounts to be identified as ribosomal structural proteins. Proteins in the large subunit are modified in vitro by cAMP-regulated protein kinases and ATP, and these modified proteins migrate with known ribosomal proteins. However, this phosphorylation has not been shown to occur in intact cells.read more
Citations
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Journal ArticleDOI
Keratin filaments of cultured human epidermal cells. Formation of intermolecular disulfide bonds during terminal differentiation.
Tung-Tien Sun,Howard Green +1 more
TL;DR: The results indicate that the uncross-linked state of the keratins in living cells is due to the reducing intracellular environment and not to a precursor state related to the primary structure of the proteins.
Journal ArticleDOI
The phosphorylation of ribosomal protein S6 in rat tissues following cycloheximide injection, in diabetes, and after denervation of diaphragm. A simple immunological determination of the extent of S6 phosphorylation on protein blots.
TL;DR: It is found that cycloheximide injection of rats gives rise to the phosphorylation of S6 in a variety of organs and tissues: diaphragm, heart and skeletal muscle liver and kidney, but not brain.
Book ChapterDOI
[45] Isolation of protein kinases from reticulocytes and phosphorylation of initiation factors
Journal ArticleDOI
Insulin‐like growth factor: insulin or serum increase phosphorylation of ribosomal protein S6 during transition of stationary chick embryo fibroblasts into early G1 phase of the cell cycle
TL;DR: It is found that within 5 min of inducing serum-deprived secondary chick embryo fibroblasts with IGF, insulin or serum to reenter the cell cycle, there is a several-fold increase in the incorporation of radioactive phosphorus into ribosomal protein S6.
Journal ArticleDOI
Changes in ribosome function by cAMP-dependent and cAMP-independent phosphorylation of ribosomal protein S6.
S J Burkhard,J A Traugh +1 more
TL;DR: The effects of phosphorylation of 40 S ribosomal subunits by protease-activated kinase I on protein synthesis could not be examined due to the rapid release of phosphate from S10 in the reconstituted translation system.
References
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Journal ArticleDOI
The reliability of molecular weight determinations by dodecyl sulfate-polyacrylamide gel electrophoresis
Klaus Weber,Mary Osborn +1 more
TL;DR: The results show that the polyacrylamide gel electrophoresis method can be used with great confidence to determine the molecular weights of polypeptide chains for a wide variety of proteins.
Journal ArticleDOI
Ribosomal proteins. VII. Two-dimensional polyacrylamide gel electrophoresis for fingerprinting of ribosomal proteins.
E. Kaltschmidt,H.G. Wittmann +1 more
TL;DR: A two-dimensional polyacrylamide gel system has been developed, improving the analytical separation of complex protein mixtures as obtained from ribosomes, and facilitates and accelerates considerably a number of investigations on the structure of ribosome.
Journal ArticleDOI
The Phosphorylation of Liver Ribosomal Proteins in Vivo EVIDENCE THAT ONLY A SINGLE SMALL SUBUNIT PROTEIN (S6) IS PHOSPHORYLATED
Axel M. Gressner,Ira G. Wool +1 more
TL;DR: It was shown by two-dimensional polyacrylamide gel electrophoresis that all of the radioactive phosphate incorporated into ribosomes was in a single small subunit protein, S6, which contained increasing numbers of radioactive phosphoserine residues.
Journal ArticleDOI
Separation of Large Quantities of Ribosomal Subunits by Zonal Ultracentrifugation
TL;DR: The maximum capacity of the B-XV zonal rotor for the separation of Escherichia coli ribosomal subunits has been investigated using a class of sucrose density gradients (hyperbolic gradients) which present certain theoretical advantages.
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The Phosphorylation of Liver Ribosomal Proteins in Vivo EVIDENCE THAT ONLY A SINGLE SMALL SUBUNIT PROTEIN (S6) IS PHOSPHORYLATED
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