Identification of the rapamycin-sensitive phosphorylation sites within the Ser/Thr-rich domain of the yeast Npr1 protein kinase

2008 ◽  
Vol 22 (23) ◽  
pp. 3743-3753 ◽  
Author(s):  
Stefan Gander ◽  
Debora Bonenfant ◽  
Patrick Altermatt ◽  
Dietmar E. Martin ◽  
Simon Hauri ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Phosphorylation Sites ◽  
Rich Domain

scholarly journals Frequency- and Afterload-Dependent Cardiac Modulation In Vivo by Troponin I With Constitutively Active Protein Kinase A Phosphorylation Sites

2004 ◽  
Vol 94 (4) ◽  
pp. 496-504 ◽  
Author(s):  
Eiki Takimoto ◽  
David G. Soergel ◽  
Paul M.L. Janssen ◽  
Linda B. Stull ◽  
David A. Kass ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Troponin I ◽  
Phosphorylation Sites ◽  
Active Protein ◽  
Cardiac Modulation ◽  
Kinase A ◽  
Constitutively Active

scholarly journals The E1^E4 Protein of Human Papillomavirus Interacts with the Serine-Arginine-Specific Protein Kinase SRPK1

2007 ◽  
Vol 81 (11) ◽  
pp. 5437-5448 ◽  
Author(s):  
Ian Bell ◽  
Ashley Martin ◽  
Sally Roberts
Keyword(s):  
Human Papillomavirus ◽  
Protein Kinase ◽  
Specific Protein ◽  
Replication Cycle ◽  
Differentiated Cells ◽  
Rich Domain ◽  
Productive Phase ◽  
High Level ◽  
Specific Protein Kinase

ABSTRACT Human papillomavirus (HPV) infections of the squamous epithelium are associated with high-level expression of the E1^E4 protein during the productive phase of infection. However, the precise mechanisms of how E1^E4 contributes to the replication cycle of the virus are poorly understood. Here, we show that the serine-arginine (SR)-specific protein kinase SRPK1 is a novel binding partner of HPV type 1 (HPV1) E1^E4. We map critical residues within an arginine-rich domain of HPV1 E1^E4, and in a region known to facilitate E1^E4 oligomerization, that are requisite for SRPK1 binding. In vitro kinase assays show that SRPK1 binding is associated with phosphorylation of an HPV1 E1^E4 polypeptide and modulates autophosphorylation of the kinase. We show that SRPK1 is sequestered into E4 inclusion bodies in terminally differentiated cells within HPV1 warts and that colocalization between E1^E4 and SRPK1 is not dependent on additional HPV1 factors. Moreover, we also identify SRPK1 binding of E1^E4 proteins of HPV16 and HPV18. Our findings indicate that SRPK1 binding is a conserved function of E1^E4 proteins of diverse virus types. SRPK1 influences important biochemical processes within the cell, including nuclear organization and RNA metabolism. While phosphorylation of HPV1 E4 by SRPK1 may directly influence HPV1 E4 function during the infectious cycle, the modulation and sequestration of SRPK1 by E1^E4 may affect the ability of SRPK1 to phosphorylate its cellular targets, thereby facilitating the productive phase of the HPV replication cycle.

scholarly journals Requirement of mosXe protein kinase for meiotic maturation of Xenopus oocytes induced by a cdc2 mutant lacking regulatory phosphorylation sites.

1992 ◽  
Vol 12 (7) ◽  
pp. 3192-3203 ◽  
Author(s):  
K M Pickham ◽  
A N Meyer ◽  
J Li ◽  
D J Donoghue
Keyword(s):  
Protein Kinase ◽  
Oocyte Maturation ◽  
Xenopus Oocytes ◽  
Germinal Vesicle ◽  
Cyclin B1 ◽  
Phosphorylation Sites ◽  
Germinal Vesicle Breakdown ◽  
Regulatory Phosphorylation

The p34cdc2 protein kinase is a component of maturation-promoting factor, the master regulator of the cell cycle in all eukaryotes. The activity of p34cdc2 is itself tightly regulated by phosphorylation and dephosphorylation. Predicted regulatory phosphorylation sites of Xenopus p34cdc2 were mutated in vitro, and in vitro-transcribed RNAs were injected into Xenopus oocytes. The cdc2 single mutants Thr-14----Ala and Tyr-15----Phe did not induce germinal vesicle breakdown (BVBD) upon microinjection into oocytes. In contrast, the cdc2 double mutant Ala-14/Phe-15 did induce GVBD. Both the Ala-14 and Ala-14/Phe-15p34cdc2 mutants were shown to coimmunoprecipitate cyclin B1 and to phosphorylate histone H1 in immune complex kinase assays. Microinjection of antisense oligonucleotides to c-mosXe was used to demonstrate the role of mos protein synthesis in the induction of GVBD by the Ala-14/Phe-15 cdc2 mutant. Thr-161 was also mutated. p34cdc2 single mutants Ala-161 and Glu-161 and triple mutants Ala-14/Phe-15/Ala-161 and Ala-14/Phe-15/Glu-161 failed to induce GVBD in oocytes and showed a decreased binding to cyclin B1 in coimmunoprecipitations. Each of the cdc2 mutants was also assayed by coinjection with cyclin B1 or c-mosXe RNA into oocytes. Several of the cdc2 mutants were found to affect the kinetics of cyclin B1 and/or mos-induced GVBD upon coinjection, although none affected the rate of progesterone-induced maturation. We demonstrate here the significance of Thr-14, Tyr-15, and Thr-161 of p34cdc2 in Xenopus oocyte maturation. In addition, these results suggest a regulatory role for mosXe in induction of oocyte maturation by the cdc2 mutant Ala-14/Phe-15.

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