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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A mutant of E. coli selected for temperature-sensitive growth on rich medium harbored an altered ribosomal protein S6 (Isono et al., 1976). This mutant was found to possess at least two mutations, one being responsible for the temperature-sensitivity and the other for the S6 alteration. Crosses with various Hfr strains as well as transductions with P 1kc revealed that the former mutation mapped at 98 min and the latter at 97 min. Furthermore, rec A derivatives of this mutant heteromerodiploid for this region possessed both the wild type and themutant forms of S6. Thus it was established that the gene at 97 min was indeed the structural gene for protein S6 (rpsF) and not a gene modifying it.
Mol Gen Genet 1977 Jun 08
PMID:A new ribosomal protein locus in Escherichia coli: the gene for protein S6 maps at 97 min. 32 9

A heat sensitive mutant of E. coli has been analyzed. A shift to restrictive temperature leads to an accumulation of ppGpp and pppGpp in both the parental and the mutant strains (both are relA+). The pool of these compounds is shown to decrease with time after the temperature shift in the case of the parental strain, but remains at the same elevated level in the case of the mutant. The temperature shift of the mutant leads to an apparent reduction of stable RNA synthesis; this inhibition can be released by chloroamphenicol or tetracycline. Gross protein synthesis is more or less unaffected at restrictive temperature. In the parental strain little effect is seen on RNA and protein synthesis after the temperature shift. A relA derivative of the mutant does not show the same inhibition of RNA synthesis at high temperature. Sedimentation analysis suggests that mutant 70S ribosome are more stable, when exposed to a lowered Mg2+ concentration, than are 70S ribosomes from the parental strain. In addition, the relative amounts of the two forms of ribosomal protein S6, which can be obtained on DEAE chromatography (Held et al., 1973), are significantly changed in the mutant.
Mol Gen Genet 1978 Apr 25
PMID:The temperature sensitive mutant 72c. II. Accumulation at high temperature of ppGpp and pppGpp in the presence of protein synthesis. 35 96

Escherichia coli has multiple forms of ribosomal protein S6, differing in number of glutamyl resideus at the C-terminal end. Three forms are revealed when crude cell extracts are fractionated by a two-dimensional gel electrophoresis technique. Pulse-chase experiments show that the shortest and most alkaline form of S6 is the first to appear. In about one doubling time this form reaches equilibrium with the two other forms of S6, implicating the existence of an enzyme, which adds glutamic acid residues to S6. We show that the relative levels of these three S6 forms are not affected by the growth rate of the culture.
Mol Gen Genet 1979 Jun 07
PMID:Post-translational modification of Escherichia coli ribosomal protein S6. 38 35

HeLa cell ribosomal protein S6, and the increase in its phosphorylation level that occurs after resuspending cells in fresh medium plus serum, were studied using two-dimensional gel electrophoresis. The maximum level of S6 phosphorylation occurs about 2 h after adding fresh medium and seum to cells that have been allowed to grow to high density; this results in an almost complete shift of the spot representing S6 in two-dimensional polacrylamide gels to a new location. Mixing experiments showed that the differences in the level of phosphorylation occur in vivo and are not an artifact of in vitro sample preparation. This method of stimulating S6 phosphorylation provides a convenient system for studying the functional significance of the phenomenon. Only one other ribosomal protein was detectably phosphorylated using [32P]-labeling and autoradiography of dried two-dimensional gels. The level of phosphorylation of this protein, L14, does not change after serum stimulation.
Mol Gen Genet 1977 Apr 29
PMID:Phosphorylation of ribosomal protein S6 in suspension cultured HeLa cells. 87 26

The intron-containing gene encoding human ribosomal protein S6 (rpS6), the major phosphoprotein in the mammalian ribosome, has been cloned. Using a PCR based cloning strategy we have isolated the rpS6 intron-containing gene in the presence of its many processed pseudogenes and determined the DNA sequence of the entire gene and its upstream and downstream flanking regions. The human rpS6 gene is 3979 bp in length and comprises six exons. Despite lacking a consensus TATA box, primer extension analysis indicates that the start of transcription is located at a single C residue within an 11 bp oligopyrimidine tract. The first exon, which contains the ATG start codon, is 48 bp in length. The DNA sequence in the 5' region of the gene has features of a CpG-rich island. Using fluorescence in situ hybridization (FISH) analysis the position of the rpS6 gene has been sublocalized to human chromosome 9p21. The similarities and differences between rpS6 and other previously characterized ribosomal protein genes are discussed.
Hum Mol Genet 1992 Nov
PMID:The organization of the intron-containing human S6 ribosomal protein (rpS6) gene and determination of its location at chromosome 9p21. 130 Nov 64

Spontaneous S6 phosphatase activities dephosphorylating Ser(P)-235 and Ser(P)-236 of the ribosomal protein S6 were measured and compared in microsomes and cytosol of rat liver. The substrate used, small (40S) ribosomal subunits 32P-labelled in vitro by protein kinase A, contained phosphorylated S6 (mainly in the diphosphorylated form) and some minor phosphorylated species. The microsomal and cytosolic S6 phosphatase activities displayed a number of distinct properties. The microsomal activity, representing ca 20% of the S6 phosphatase activity in the post-mitochondrial supernatant, was mainly due to a type-1 phosphatase and dephosphorylated only S6. The remaining post-mitochondrial S6 phosphatase activity, which was fully recovered in the cytosol, and appeared to result from a combination of type-1 (43%) and type 2 (57%) phosphatases, acted on S6 as well as on the minor phosphorylated species. The microsomal activity was 50% inhibited by MgCl2 (10 mM) and was stimulated at least 4.3 fold by MnCl2 (1 mM), while the cytosolic activity was inhibited only 18% by Mg2+ (10 mM) and was increased 2.2 fold by Mn2+ (1 mM). The microsomal activity was increased 10% (P less than 0.06) by lower doses of insulin (25 U/Kg) and 14% (P less than 0.05) by vanadate, but was not significantly (P greater than 0.10) affected by larger doses of insulin (100 U/kg), hepatectomy or cycloheximide. By comparison the cytosolic S6 phosphatase activity was unresponsive to insulin and vanadate, but was decreased 14% and 17% (P less than 0.05) by hepatectomy and cycloheximide.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Biochem 1991 Oct 16
PMID:A comparative study of microsomal and cytosolic S6 phosphatase activities in rat liver. 166 99

Phosphorylation of ribosomal protein S6 of mammals precedes activation of cell growth in numerous biological systems. We have cloned a cDNA for ribosomal protein S6 from T-47D human breast cancer cells by immunoscreening a lambda gt11 expression library with antibody raised against the mitochondrial Ca(2+)-binding ATPase inhibitor protein (CaBI) of bovine heart mitochondria (Yamada & Huzel: J Biol Chem 263: 11498-11503, 1988). Similar clones were obtained by the immunoscreening of a rat heart expression library. In agreement with others, the open reading frames of the cDNAs from the two species coded for the same amino acid sequence. No difference in S6 of the human neoplastic cells compared to that of non-neoplastic cells was found. However, common antigenic determinants in S6 and CaBI were indicated. Accordingly, S6 was purified from rat liver ribosomes and antiserum prepared. Immuno-dot blot and Western blot analyses showed high specific reactivity between S6, the cloned chimeric beta-galactosidase fusion protein from a cDNA clone, and CaBI with anti-S6 and anti-CaBI antibodies. The antibodies also showed a high degree of discrimination for S6 and CaBI. Neither interacted with the other ribosomal proteins nor with another ATPase inhibitor protein from bovine heart mitochondria. Neither interacted with the Ca(2+)-binding proteins, calmodulin, oncomodulin, Protein C, or Factor X. Prothrombin was weakly reactive with anti-CaBI but not with anti-S6. Thus, the results fulfill the specific criteria for the concept and operational definition of common protein epitopes in S6 and CaBI. However, neither prothrombin nor S6 fusion protein inhibited mitochondrial ATPase activity even at 20 times the concentrations at which CaBI gave 97% inhibition.
Mol Cell Biochem 1991 Nov 13
PMID:Antigenic reactivity of ribosomal protein S6 and the calcium-binding ATPase inhibitor protein of mammalian mitochondria. 183 89

Mitogen-activated protein (MAP) kinase is a serine/threonine-specific protein kinase which is activated in response to various mitogenic agonists (e.g., epidermal growth factor, insulin, and the tumor promoter tetradecanoyl phorbol acetate [TPA]) and requires both threonine and tyrosine phosphorylation for activity. This enzyme has recently been shown to be identical or closely related to pp42, a protein which becomes tyrosine phosphorylated in response to mitogenic stimulation. Neither the kinases which regulate MAP kinase/pp42 nor the in vivo substrates for this enzyme are known. Because MAP MAP kinase is activated and phosphorylated in response both to agents which stimulate tyrosine kinase receptors and to agents which stimulate protein kinase C, a serine/threonine kinase, we have examined the regulation and phosphorylation of this enzyme in 3T3-TNR9 cells, a variant cell line partially defective in protein kinase C-mediated signalling. In this communication, we show that in the 3T3-TNR9 variant cell line, TPA does not cause the characteristically rapid phosphorylation of pp42 or the activation and phosphorylation of MAP kinase. This defective response is not due to the absence of the MAP kinase/pp42 protein itself because both tyrosine phosphorylation of MAP kinase/pp42 and its enzymatic activation could be induced by platelet-derived growth factor in the 3T3-TNR9 cells. Thus, the defect in these variant cells apparently resides in some aspect of the regulation of MAP kinase phosphorylation. Since the 3T3-TNR9 cells are also defective with respect to the TPA-induced increase in ribosomal protein S6 kinase, these in vivo results reinforce the earlier in vitro finding that MAP kinase can regulate S6 kinase activity. These findings suggest a key role for MAP kinase in a kinase cascade cascade involved in the control of cell proliferation.
Mol Cell Biol 1991 Feb
PMID:Defective regulation of mitogen-activated protein kinase activity in a 3T3 cell variant mitogenically nonresponsive to tetradecanoyl phorbol acetate. 199 Feb 61

Modifications of ribosomes have been investigated in human epidermoid carcinoma-2 cells at different stages of herpes simplex virus type 1 infection. Very early in infection, there is an increase in ribosomal protein S6 phosphorylation even in the absence of serum. The same result is obtained in the presence of actinomycin D. At early infection time, ribosomal proteins S2, S3a and Sa are newly phosphorylated. At early and early-late times, three phosphorylated non-ribosomal proteins (v1, v2 and v3) are differently associated temporally to ribosomes. Analyses of proteins extracted from 40S subunits, 80S ribosomes and polysomes show that v1 and v2 are distributed differently among the different ribosomal populations. S6 phosphopeptides were found to be identical after serum stimulation and after viral infection. In every case phosphoserine and phosphothreonine were identified in S6. Only phosphoserine was found in other phosphorylated proteins. Our results indicate that herpes simplex virus type 1 is able to modify pre-existing ribosomes: (i) by stimulating a pre-existing kinase for S6 phosphorylation even in the absence of serum and of viral genome expression; (ii) by inducing new specific kinase activity(ies); and (iii) by association of new, phosphorylated proteins to ribosomes. These ribosomal modifications are correlated with changes in protein synthesis, as shown by two-dimensional electrophoretic analyses of newly synthesized 35S-labelled proteins.
Mol Gen Genet 1990 Feb
PMID:Ribosome and protein synthesis modifications after infection of human epidermoid carcinoma cells with herpes simplex virus type 1. 216 50

Antiserum raised against recombinant Xenopus ribosomal protein S6 kinase (rsk) was used to identify a 90,000-Mr ribosomal S6 kinase, pp90rsk, in chicken embryo fibroblasts. Adding serum to cells stimulated the phosphorylation of pp90rsk on serine and threonine residues and increased the activity of S6 kinase measured in immune complex assays. Xenopus S6 kinase II and chicken embryo fibroblast pp90rsk had nearly identical phosphopeptide maps.
Mol Cell Biol 1990 May
PMID:Identification of mitogen-responsive ribosomal protein S6 kinase pp90rsk, a homolog of Xenopus S6 kinase II, in chicken embryo fibroblasts. 232 57


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