Control of ribosomal protein phosphorylation in HeLa cells

Lastick, Stanley M.; McConkey, Edwin H.

doi:10.1016/0006-291x(80)91560-0

Cited by 53 publications

(26 citation statements)

References 9 publications

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“…The identical phosphopeptide pattern obtained in our system after stimulation with two different types of agonists contrasts with other systems where different agonists led also to different phosphopeptide patterns of S6, as shown for the effects of insulin vs dibutyryl-CAMP in HeLa cells [13] and for the effects of glucagon vs insulin in isolated hepatocytes [ 121. …”

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Phosphopeptide patterns of the ribosomal protein S6 following stimulation of guineapig parotid glands by secretagogues involving either cAMP or calcium as second messenger

Padel¹,

Kruppa²,

Jahn³

et al. 1983

FEBS Letters

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Stimulation of secretion in exocrine cells is associated with the incorporation of up to 3 to 4 phosphates into the ribosomal protein S6. This occurs with secretagogues involving either cAMP or free calcium as second messenger. An analysis of the phosphorylation pattern of S6 from stimulated guineapig parotid glands reveals 3 phosphopeptides (termed A,B,C). The phosphopeptide pattern was identical for cAMP‐ or calcium‐mediated stimulation, whereas phosphorylation of the S6 protein in vitro with catalytic subunit of cAMP‐dependent protein kinase resulted only in the formation of phosphopeptides A and C. Therefore, secretagogue‐mediated phosphorylation is not or not exclusively catalyzed by cAMP‐dependent protein kinase even when cAMP is the second messenger.

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“…For reticulocytes it has been shown [9] that some of the phosphopeptides derived after phosphorylation in vivo could be phosphorylated in vitro by the catalytic subunit of cAMPdPK. For hepatocytes [ 121 and HeLa cells [13] it has been shown, that different agonists led to significantly different phosphopeptide patterns of S6.…”

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confidence: 99%

Phosphopeptide patterns of the ribosomal protein S6 following stimulation of guineapig parotid glands by secretagogues involving either cAMP or calcium as second messenger

Padel¹,

Kruppa²,

Jahn³

et al. 1983

FEBS Letters

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“…Upon mitogenic stimulation, the entire complement of 6 x 106 ribosomes in cultured cells (1) or the 1012 ribosomes in Xenopus oocytes (2) becomes rapidly phosphorylated (3)(4)(5)(6)(7)(8). Nearly all of the phosphate is incorporated into a single protein, S6.…”

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A Xenopus ribosomal protein S6 kinase has two apparent kinase domains that are each similar to distinct protein kinases.

Jones

Erikson

Blenis

et al. 1988

Proc. Natl. Acad. Sci. U.S.A.

265

170

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We report the molecular cloning of cDNAs for S6 kinase H (S6K11) mRNAs present in Xenopus ovarian tissue. Two cDNAs were isolated by hybridization to oligonucleotide probes designed to encode tryptic peptides isolated from S6KII. The two cDNAs show 91% sequence similarity to each other. These two cDNAs predict proteins of 733 (S6Klla) and 629 (S6KII) amino acids that show 95% sequence similarity over the 629 amino acids where they are colinear. Amino acids 44-733 of S6KIIa were expressed in Escherichia coli and the recombinant protein was used to raise antiserum in rabbits. This antiserum reacted with authentic S6KII prepared from Xenopus eggs. This interaction was specifically blocked by the recombinant protein from E. coli. The sequences of S6KIIa and -13 predict four tryptic peptides whose sequences are identical to four peptides isolated from a tryptic digest of S6KII. The S6KII proteins have a very unusual structure when compared with previously studied protein kinases. They contain two apparent kinase domains, each similar to distinct protein kinases. The amino-terminal 366 amino acids show high sequence similarity to the regions of protein kinase C, the catalytic subunit of cAMP-dependent protein kinase, and cGMP-dependent protein kinase that contain the sites for ATP binding and are believed to be the catalytic centers for phosphotransferase activity. The remainder of the S6 kinase molecule shows high sequence similarity to the ATP-binding and presumed catalytic domain ofthe catalytic subunit of phosphorylase b kinase.The activation of a vigorous serine-specific protein kinase and the concomitant phosphorylation of ribosomes is a highly conserved response of animal cells to mitogenic stimulation. Upon mitogenic stimulation, the entire complement of 6 x 106 ribosomes in cultured cells (1) or the 1012 ribosomes in Xenopus oocytes (2) becomes rapidly phosphorylated (3-8). Nearly all of the phosphate is incorporated into a single protein, S6. This event is mediated by a protein kinase activity that can be detected readily by phosphorylation of 40S subunits in vitro. The regulation of this enzyme activity is of interest because of the wide variety of agents that activate the kinase including serum, oncogene products, and phorbol ester in cultured cells (9-11) and insulin and progesterone in Xenopus oocytes (12, 13). Although these agents initially act through different receptors, the pathways apparently converge to activate a single enzyme or a limited number of distinct enzymes.To date, the most highly purified example of an S6 kinase, denoted S6KII, has been obtained from unfertilized Xenopus eggs (14,15). This enzyme has an apparent Mr of 92,000 as determined by NaDodSO4/PAGE. Antiserum raised against purified S6KII is capable of immunoprecipitating S6 kinase activity that can be measured in an immune complex. Studies with this antiserum have revealed that progesterone-or insulin-stimulated oocytes contain an antigenically related enzyme. Furthermore, anti-S6KII antiserum reacts with an S6 kinase a...

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“…The phosphorylation of S6 is rapidly increased by treatment of quiescent cells with serum, with a variety of mitogenic agents, or with the tumor promoter phorbol 12-myristate 13-acetate (PMA) (5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Furthermore, even in the absence of such stimulating agents, S6 remains highly phosphorylated in cells transformed by several oncogenic viruses (15)(16)(17).…”

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Regulation of a ribosomal protein S6 kinase activity by the Rous sarcoma virus transforming protein, serum, or phorbol ester.

Blenis¹,

Erikson²

1985

Proc. Natl. Acad. Sci. U.S.A.

102

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Protein kinase capable of phosphorylating 40S ribosomal protein S6 on serine residues has been detected in chicken embryo fibroblasts. This activity appears to be regulated in direct response to expression of pp6Ovsrc in chicken embryo fibroblasts infected with a temperature-sensitive transformation mutant of Rous sarcoma virus. Partially purified S6 kinase was highly specific for S6 in 40S ribosomal subunits. The S6 kinase was not inhibited by calcium or by the heat-stable inhibitor of cAMP-dependent protein kinase, nor was it activated by phosphatidylserine, diacylglycerol, and calcium. Thus, it is distinct from protein kinase C and cAMP-dependent protein kinase, which are capable of phosphorylating S6 in vitro. The tumor-promoter phorbol 12-myristate 13-acetate also stimulated ribosomal protein S6 kinase activity in serumstarved chicken embryo fibroblasts, whereas phorbol, the inactive analog of phorbol 12-myristate 13-acetate, had no effect. S6 kinase activity stimulated by expression of pp60vzrc, by phorbol 12-myristate 13-acetate, or by serum growth factors exhibited similar chromatographic properties upon ion-exchange chromatography. These results suggest that a common protein kinase may be activated by three diverse stimuli all involved in regulating cell proliferation.Modification of proteins by reversible phosphorylation has been shown to alter many cellular biochemical processes. The regulation of protein function through the phosphorylation of serine and/or threonine residues is well documented (1). During the past few years a number of oncogene products have been shown to be protein kinases specific for tyrosine residues (for reviews, see refs. 2 and 3), and a similar activity is associated with the membrane receptors for several growth factors (4). Changes in protein function as a result of phosphorylation on tyrosine residues have not been demonstrated. Nevertheless, a strong correlation exists between the expression of tyrosine-specific protein kinase activity and altered metabolism in cells transformed by retroviruses or stimulated by growth factors. Several transforming gene products and growth factors also stimulate the modification of proteins on serine residues presumably by altering the activity and/or the level of serine-specific protein kinase(s) and/or phosphoprotein phosphatase(s). One such protein of potential physiological importance is ribosomal protein S6.The phosphorylation of S6 is rapidly increased by treatment of quiescent cells with serum, with a variety of mitogenic agents, or with the tumor promoter phorbol 12-myristate 13-acetate (PMA) (5-14). Furthermore, even in the absence of such stimulating agents, S6 remains highly phosphorylated in cells transformed by several oncogenic viruses (15)(16)(17).Several lines of evidence link elevated S6 phosphorylation to initiation of protein synthesis, suggesting that this may be one of several events involved in the control of cell proliferation (11,(18)(19)(20)(21)(22). As a result, much effort has been directed recently to id...

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Control of ribosomal protein phosphorylation in HeLa cells

Cited by 53 publications

References 9 publications

Phosphopeptide patterns of the ribosomal protein S6 following stimulation of guineapig parotid glands by secretagogues involving either cAMP or calcium as second messenger

Phosphopeptide patterns of the ribosomal protein S6 following stimulation of guineapig parotid glands by secretagogues involving either cAMP or calcium as second messenger

A Xenopus ribosomal protein S6 kinase has two apparent kinase domains that are each similar to distinct protein kinases.

Regulation of a ribosomal protein S6 kinase activity by the Rous sarcoma virus transforming protein, serum, or phorbol ester.

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