scholarly journals Protein kinase activity in RNA-binding proteins of Amphibia oocytes

FEBS Letters ◽  
1982 ◽  
Vol 141 (2) ◽  
pp. 157-160 ◽  
Author(s):  
A.S. Stepanov ◽  
K.V. Kandror ◽  
S.M. Elizarov
Keyword(s):  
Protein Kinase ◽  
Binding Proteins ◽  
Kinase Activity ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Protein Kinase Activity

scholarly journals Cyclic AMP-binding and cyclic AMP-dependent protein kinase activities in the cytosol of differentiating bone marrow erythroblasts

1981 ◽  
Vol 196 (3) ◽  
pp. 893-897 ◽  
Author(s):  
M S Setchenska ◽  
J G Vassileva-Popova ◽  
H R Arnstein
Keyword(s):  
Bone Marrow ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Binding Proteins ◽  
Kinase Activity ◽  
Binding Capacity ◽  
Protein Kinase Activity ◽  
Dependent Protein Kinase ◽  
Dividing Cells ◽  
Dependent Protein

Cytosolic cyclic AMP-binding capacity and cyclic AMP-dependent protein kinase activity have been studied in relation to differentiation and maturation of rabbit bone marrow erythroblasts. Using cells fractionated by velocity sedimentation at unit gravity, it was found that both activities decreased in dividing cells when calculated in terms of cell number but remained constant per cell volume. After the final cell division, cyclic AMP-dependent protein kinase activity did not change further, whereas cyclic AMP-binding capacity declined. There were no qualitative, but only quantitative, changes in the cyclic AMP-binding proteins that are present in the cytosol of developing erythroblasts. In the immature cells, the apparent KD for the interaction of binding proteins with cyclic AMP was 4 } 10(-8) M. The data suggest that changes in cyclic AMP-binding activity during differentiation of erythroid cells are due both to changes in the amount of binding proteins and in their affinity for cyclic AMP. Plasma membranes of erythroblasts were also able to bind cyclic AMP but only in dividing cells.

scholarly journals Phosphorylation of mRNA-Binding Proteins Puf1 and Puf2 by TORC2-Activated Protein Kinase Ypk1 Alleviates Their Repressive Effects

Membranes ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 500
Author(s):  
Henri A. Galez ◽  
Françoise M. Roelants ◽  
Sarah M. Palm ◽  
Kendra K. Reynaud ◽  
Nicholas T. Ingolia ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Protein Kinase ◽  
Binding Proteins ◽  
Rna Binding ◽  
Fluorescent Protein ◽  
Rna Binding Proteins ◽  
Physiological Role ◽  
Rna Recognition Motif ◽  
Associated Proteins

Members of the Puf family of RNA-binding proteins typically associate via their Pumilio homology domain with specific short motifs in the 3’-UTR of an mRNA and thereby influence the stability, localization and/or efficiency of translation of the bound transcript. In our prior unbiased proteome-wide screen for targets of the TORC2-stimulated protein kinase Ypk1, we identified the paralogs Puf1/Jsn1 and Puf2 as high-confidence substrates. Earlier work by others had demonstrated that Puf1 and Puf2 exhibit a marked preference for interaction with mRNAs encoding plasma membrane-associated proteins, consistent with our previous studies documenting that a primary physiological role of TORC2-Ypk1 signaling is maintenance of plasma membrane homeostasis. Here, we show, first, that both Puf1 and Puf2 are authentic Ypk1 substrates both in vitro and in vivo. Fluorescently tagged Puf1 localizes constitutively in cortical puncta closely apposed to the plasma membrane, whereas Puf2 does so in the absence of its Ypk1 phosphorylation, but is dispersed in the cytosol when phosphorylated. We further demonstrate that Ypk1-mediated phosphorylation of Puf1 and Puf2 upregulates production of the protein products of the transcripts to which they bind, with a concomitant increase in the level of the cognate mRNAs. Thus, Ypk1 phosphorylation relieves Puf1- and Puf2-mediated post-transcriptional repression mainly by counteracting their negative effect on transcript stability. Using a heterologous protein-RNA tethering and fluorescent protein reporter assay, the consequence of Ypk1 phosphorylation in vivo was recapitulated for full-length Puf1 and even for N-terminal fragments (residues 1-340 and 143-295) corresponding to the region upstream of its dimerization domain (an RNA-recognition motif fold) encompassing its two Ypk1 phosphorylation sites (both also conserved in Puf2). This latter result suggests that alleviation of Puf1-imposed transcript destabilization does not obligatorily require dissociation of Ypk1-phosphorylated Puf1 from a transcript. Our findings add new insight about how the TORC2-Ypk1 signaling axis regulates the content of plasma membrane-associated proteins to promote maintenance of the integrity of the cell envelope.

scholarly journals RNA-Binding Protein Rnc1 Regulates Cell Length at Division and Acute Stress Response in Fission Yeast through Negative Feedback Modulation of the Stress-Activated Mitogen-Activated Protein Kinase Pathway

mBio ◽  
2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Francisco Prieto-Ruiz ◽  
Jero Vicente-Soler ◽  
Alejandro Franco ◽  
Elisa Gómez-Gil ◽  
Marta Sánchez-Marinas ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Fission Yeast ◽  
Binding Proteins ◽  
Rna Binding ◽  
Acute Stress ◽  
Rna Binding Proteins ◽  
Cell Length ◽  
Mitogen Activated Protein Kinase ◽  
Content Type ◽  
Mitogen Activated Protein

ABSTRACT RNA-binding proteins (RBPs) play a major role during control of mRNA localization, stability, and translation and are central to most cellular processes. In the fission yeast Schizosaccharomyces pombe, the multiple K homology (KH) domain RBP Rnc1 downregulates the activity of the cell integrity pathway (CIP) via stabilization of pmp1+ mRNA, which encodes the Pmp1 phosphatase that inactivates Pmk1, the mitogen-activated protein kinase (MAPK) component of this signaling cascade. However, Rnc1 likely regulates the half-life/stability of additional mRNAs. We show that Rnc1 downregulates the activity of Sty1, the MAPK of the stress-activated MAPK pathway (SAPK), during control of cell length at division and recovery in response to acute stress. Importantly, this control strictly depends on Rnc1’s ability to bind mRNAs encoding activators (Wak1 MAPKKK, Wis1 MAPKK) and downregulators (Atf1 transcription factor, Pyp1 and Pyp2 phosphatases) of Sty1 phosphorylation through its KH domains. Moreover, Sty1 is responsible for Rnc1 phosphorylation in vivo at multiple phosphosites during growth and stress, and these modifications trigger Rnc1 for proper binding and destabilization of the above mRNA targets. Phosphorylation by Sty1 prompts Rnc1-dependent mRNA destabilization to negatively control SAPK signaling, thus revealing an additional feedback mechanism that allows precise tuning of MAPK activity during unperturbed cell growth and stress. IMPORTANCE Control of mRNA localization, stability, turnover, and translation by RNA-binding proteins (RBPs) influences essential processes in all eukaryotes, including signaling by mitogen-activated protein kinase (MAPK) pathways. We describe that in the fission yeast Schizosaccharomyces pombe the RBP Rnc1 negatively regulates cell length at division during unperturbed growth and recovery after acute stress by reducing the activity of the MAPK Sty1, which regulates cell growth and differentiation during environmental cues. This mechanism relies on Rnc1 binding to specific mRNAs encoding both enhancers and negative regulators of Sty1 activity. Remarkably, multiple phosphorylation of Rnc1 by Sty1 favors RBP binding and destabilization of the above mRNAs. Thus, posttranscriptional modulation of MAP kinase signaling by RNA-binding proteins emerges as a major regulatory mechanism that dictates the growth cycle and cellular adaptation in response to the changing environment in eukaryotic organisms.

scholarly journals Translational regulation of lipoprotein lipase in adipocytes: depletion of cellular protein kinase Cα activates binding of the C subunit of protein kinase A to the 3′-untranslated region of the lipoprotein lipase mRNA

2008 ◽  
Vol 413 (2) ◽  
pp. 315-322 ◽  
Author(s):  
Resat Unal ◽  
Irina Pokrovskaya ◽  
Preeti Tripathi ◽  
Brett P. Monia ◽  
Philip A. Kern ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Lipoprotein Lipase ◽  
Untranslated Region ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Protein Kinase Cα ◽  
Translational Inhibition ◽  
Kinase A

Adipose LPL (lipoprotein lipase) plays an important role in regulating plasma triacylglycerols and lipid metabolism. We have previously demonstrated that PKCα (protein kinase Cα) depletion inhibits LPL translation in 3T3-F442A adipocytes. Using in vitro translation experiments, the minimum essential region on the 3′UTR (3′-untranslated region) of LPL mRNA required for the inhibition of translation was identified as the proximal 39 nt. These results were confirmed by RNase protection analysis using cytoplasmic proteins isolated from the adipocytes treated with PKCα antisense oligomers and the LPL 3′UTR transcript (LPL 3′UTR nt: 1512–1640). The protein components involved in this RNA-binding interaction from PKCα depletion were passed through an affinity column containing a sequence of the LPL 3′UTR and, after Western blotting, the RNA-binding proteins were identified as the catalytic and the regulatory subunits of PKA (protein kinase A), Cα and RIIβ, and AKAP (A-kinase-anchoring protein) 121. This RNA inhibitory complex consisted of the same RNA-binding proteins that have been identified previously as mediators of LPL translational inhibition by PKA activation, suggesting that PKCα depletion inhibits LPL translation through PKA activation. In additional experiments, PKC depletion by prolonged PMA treatment or PKCα antisense oligomers resulted in an increase in PKA activity in 3T3-F442A adipocytes, comparable with PKA activation with adrenaline (epinephrine) treatment. These results demonstrate that LPL translational inhibition occurs through an RNA-binding complex involving PKA subunits and AKAP121, and this complex can be activated either through traditional PKA activation methods or through the depletion of PKCα.

Effect of Thrombin on Phosphorylation of Platelet Membrane Proteins

1976 ◽  
Vol 35 (03) ◽  
pp. 635-642 ◽  
Author(s):  
M Steiner
Keyword(s):  
Protein Kinase ◽  
Kinase Activity ◽  
Qualitative Change ◽  
Protein Kinase Activity ◽  
Protein Substrates ◽  
Phosphoprotein Phosphatase ◽  
Progressive Loss ◽  
Platelet Membranes ◽  
Endogenous Protein ◽  
Considerable Loss

SummaryThe effect of thrombin on the phosphorylating activity of platelet membranes was compared to that of trypsin. Preincubation of non-32P phosphorylated platelet membranes with or without either of these two enzymes resulted in a considerable loss of membrane protein kinase activity which was most severe when trypsin was used. Protein kinase activity and endogenous protein acceptors decreased in parallel. 32P-phosphorylated membranes showed a slow but progressive loss of label which was accelerated by trypsin. Thrombin under these conditions prevented the loss of 32P-phosphate. These results are interpreted to indicate a thrombin-induced destruction of a phosphoprotein phosphatase. The protein kinase activity of phosphorylated platelet membranes using endogenous or exogenous protein substrates showed a significant reduction compared to non-phosphorylated membranes suggesting a deactivation of protein kinase by phosphorylation of platelet membranes. Neither thrombin nor trypsin caused a qualitative change in the membrane polypeptides accepting 32P-phosphate but resulted in quantitative alterations of their ability to become phosphorylated.

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