scholarly journals Regulation and properties of extracellular signal-regulated protein kinases 1, 2, and 3.

1993 ◽  
Vol 4 (5) ◽  
pp. 1104-1110
Author(s):  
D J Robbins ◽  
E Zhen ◽  
M Cheng ◽  
S Xu ◽  
C A Vanderbilt ◽  
...  
Keyword(s):  
Protein Kinases ◽  
Cytoskeletal Proteins ◽  
Regulatory Proteins ◽  
Wild Type ◽  
Catalytic Core ◽  
Extracellular Signal ◽  
Pleiotropic Action ◽  
Kinase Cascade ◽  
Protein Kinase Cascade

The extracellular signal-regulated kinases ERK1 and ERK2 are 43- and 41-kd enzymes activated by many extracellular cues. They lie within a protein kinase cascade that is used to achieve many cellular responses. In addition to the wide variety of regulatory contexts in which they are activated, they phosphorylate important regulatory proteins, including receptors, transcription factors, cytoskeletal proteins, and other protein kinases. Thus, the stimulation of this kinase cascade is thought to have a pleiotropic action. ERK1 and ERK2 are controlled by phosphorylation on threonine and tyrosine. To understand the regulatory mechanisms, wild-type and mutant ERKs were expressed in bacteria and phosphorylated with MEK, the enzyme that is upstream of ERKs. Wild-type proteins could be activated 500- to 1,000-fold in vitro by MEK. ERK3, an enzyme of 62 kd and only 50% identical to ERK1 and ERK2 in the catalytic core, was also phosphorylated by MEK in vitro. This suggests that all three of these enzymes are targets of common signaling pathways.

scholarly journals Substrate specificities of tyrosine-specific protein kinases toward cytoskeletal proteins in vitro.

1986 ◽  
Vol 261 (31) ◽  
pp. 14797-14803 ◽  
Author(s):  
T Akiyama ◽  
T Kadowaki ◽  
E Nishida ◽  
T Kadooka ◽  
H Ogawara ◽  
...  
Keyword(s):  
Protein Kinases ◽  
Specific Protein ◽  
Cytoskeletal Proteins ◽  
Substrate Specificities

A yeast mitogen-activated protein kinase homolog (Mpk1p) mediates signalling by protein kinase C

1993 ◽  
Vol 13 (5) ◽  
pp. 3067-3075 ◽  
Author(s):  
K S Lee ◽  
K Irie ◽  
Y Gotoh ◽  
Y Watanabe ◽  
H Araki ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Map Kinase ◽  
Protein Kinases ◽  
Map Kinases ◽  
Pheromone Response ◽  
Pheromone Response Pathway ◽  
Kinase C ◽  
Mitogen Activated Protein ◽  
Kinase Cascade ◽  
Protein Kinase Cascade

Mitogen-activated protein (MAP) kinases are activated in response to a variety of stimuli through a protein kinase cascade that results in their phosphorylation on tyrosine and threonine residues. The molecular nature of this cascade is just beginning to emerge. Here we report the isolation of a Saccharomyces cerevisiae gene encoding a functional analog of mammalian MAP kinases, designated MPK1 (for MAP kinase). The MPK1 gene was isolated as a dosage-dependent suppressor of the cell lysis defect associated with deletion of the BCK1 gene. The BCK1 gene is also predicted to encode a protein kinase which has been proposed to function downstream of the protein kinase C isozyme encoded by PKC1. The MPK1 gene possesses a 1.5-kb uninterrupted open reading frame predicted to encode a 53-kDa protein. The predicted Mpk1 protein (Mpk1p) shares 48 to 50% sequence identity with Xenopus MAP kinase and with the yeast mating pheromone response pathway components, Fus3p and Kss1p. Deletion of MPK1 resulted in a temperature-dependent cell lysis defect that was virtually indistinguishable from that resulting from deletion of BCK1, suggesting that the protein kinases encoded by these genes function in a common pathway. Expression of Xenopus MAP kinase suppressed the defect associated with loss of MPK1 but not the mating-related defects associated with loss of FUS3 or KSS1, indicating functional conservation between the former two protein kinases. Mutation of the presumptive phosphorylated tyrosine and threonine residues of Mpk1p individually to phenylalanine and alanine, respectively, severely impaired Mpk1p function. Additional epistasis experiments, and the overall architectural similarity between the PKC1-mediated pathway and the pheromone response pathway, suggest that Pkc1p regulates a protein kinase cascade in which Bck1p activates a pair of protein kinases, designated Mkk1p and Mkk2p (for MAP kinase-kinase), which in turn activate Mpk1p.

scholarly journals The Flagellar Motility ofChlamydomonas pf25 Mutant Lacking an AKAP-binding Protein Is Overtly Sensitive to Medium Conditions

2006 ◽  
Vol 17 (1) ◽  
pp. 227-238 ◽  
Author(s):  
Chun Yang ◽  
Pinfen Yang
Keyword(s):  
Regulatory Proteins ◽  
Flagellar Motility ◽  
Wild Type ◽  
Dependent Protein Kinase ◽  
Wide Range ◽  
Anchoring Protein ◽  
Radial Spokes ◽  
Dependent Protein ◽  
Cilia And Flagella

Radial spokes are a conserved axonemal structural complex postulated to regulate the motility of 9 + 2 cilia and flagella via a network of phosphoenzymes and regulatory proteins. Consistently, a Chlamydomonas radial spoke protein, RSP3, has been identified by RII overlays as an A-kinase anchoring protein (AKAP) that localizes the cAMP-dependent protein kinase (PKA) holoenzyme by binding to the RIIa domain of PKA RII subunit. However, the highly conserved docking domain of PKA is also found in the N termini of several AKAP-binding proteins unrelated to PKA as well as a 24-kDa novel spoke protein, RSP11. Here, we report that RSP11 binds to RSP3 directly in vitro and colocalizes with RSP3 toward the spoke base near outer doublets and dynein motors in axonemes. Importantly, RSP11 mutant pf25 displays a spectrum of motility, from paralysis with flaccid or twitching flagella as other spoke mutants to wild-typelike swimming. The wide range of motility changes reversibly depending on the condition of liquid media without replacing defective proteins. We postulate that radial spokes use the RIIa/AKAP module to regulate ciliary and flagellar beating; absence of the spoke RIIa protein exposes a medium-sensitive regulatory mechanism that is not obvious in wild-type Chlamydomonas.

scholarly journals Mitogen-activated protein kinase kinase 1 (MKK1) is negatively regulated by threonine phosphorylation

1994 ◽  
Vol 14 (3) ◽  
pp. 1594-1602
Author(s):  
A J Rossomando ◽  
P Dent ◽  
T W Sturgill ◽  
D R Marshak
Keyword(s):  
Protein Kinase ◽  
Phosphorylation Site ◽  
Mitogen Activated Protein Kinase ◽  
Dual Specificity ◽  
Mitogen Activated Protein ◽  
Kinase Cascade ◽  
Protein Kinase Cascade ◽  
Protein Kinase Kinase

Mitogen-activated protein kinase kinase 1 (MKK1), a dual-specificity tyrosine/threonine protein kinase, has been shown to be phosphorylated and activated by the raf oncogene product as part of the mitogen-activated protein kinase cascade. Here we report the phosphorylation and inactivation of MKK1 by phosphorylation on threonine 286 and threonine 292. MKK1 contains a consensus phosphorylation site for p34cdc2, a serine/threonine protein kinase that regulates the cell division cycle, at Thr-286 and a related site at Thr-292. p34cdc2 catalyzes the in vitro phosphorylation of MKK1 on both of these threonine residues and inactivates MKK1 enzymatic activity. Both sites are phosphorylated in vivo as well. The data presented in this report provide evidence that MKK1 is negatively regulated by threonine phosphorylation.

Wild type Kirsten rat sarcoma is a novel microRNA-622-regulated therapeutic target for hepatocellular carcinoma and contributes to sorafenib resistance

Gut ◽  
2017 ◽  
Vol 67 (7) ◽  
pp. 1328-1341 ◽  
Author(s):  
Peter Dietrich ◽  
Andreas Koch ◽  
Valerie Fritz ◽  
Arndt Hartmann ◽  
Anja Katrin Bosserhoff ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Functional Analysis ◽  
Protein Kinase ◽  
Advanced Hepatocellular Carcinoma ◽  
Wild Type ◽  
Sorafenib Treatment ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
Hcc Cells

ObjectiveSorafenib is the only effective therapy for advanced hepatocellular carcinoma (HCC). Combinatory approaches targeting mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK)- and phosphatidylinositol-4,5-bisphosphate-3-kinase (PI3K)/protein-kinase B(AKT) signalling yield major therapeutic improvements. RAS proteins regulate both RAF/MAPK and PI3K/AKT signalling. However, the most important RAS isoform in carcinogenesis, Kirsten rat sarcoma (KRAS), remains unexplored in HCC.DesignHuman HCC tissues and cell lines were used for expression and functional analysis. Sorafenib-resistant HCC cells were newly generated. RNA interference and the novel small molecule deltarasin were used for KRAS inhibition both in vitro and in a murine syngeneic orthotopic HCC model.ResultsExpression of wild type KRAS messenger RNA and protein was increased in HCC and correlated with extracellular-signal regulated kinase (ERK) activation, proliferation rate, advanced tumour size and poor patient survival. Bioinformatic analysis and reporter assays revealed that KRAS is a direct target of microRNA-622. This microRNA was downregulated in HCC, and functional analysis demonstrated that KRAS-suppression is the major mediator of its inhibitory effect on HCC proliferation. KRAS inhibition markedly suppressed RAF/ERK and PI3K/AKT signalling and proliferation and enhanced apoptosis of HCC cells in vitro and in vivo. Combinatory KRAS inhibition and sorafenib treatment revealed synergistic antitumorigenic effects in HCC. Sorafenib-resistant HCC cells showed elevated KRAS expression, and KRAS inhibition resensitised sorafenib-resistant cells to suppression of proliferation and induction of apoptosis.ConclusionsKRAS is dysregulated in HCC by loss of tumour-suppressive microRNA-622, contributing to tumour progression, sorafenib sensitivity and resistance. KRAS inhibition alone or in combination with sorafenib appears as novel promising therapeutic strategy for HCC.

scholarly journals Regulation and properties of extracellular signal-regulated protein kinases 1 and 2 in vitro.

1993 ◽  
Vol 268 (7) ◽  
pp. 5097-5106
Author(s):  
D.J. Robbins ◽  
E. Zhen ◽  
H. Owaki ◽  
C.A. Vanderbilt ◽  
D. Ebert ◽  
...  
Keyword(s):  
Protein Kinases ◽  
Extracellular Signal

scholarly journals Dominant TEL1-hy Mutations Compensate for Mec1 Lack of Functions in the DNA Damage Response

2007 ◽  
Vol 28 (1) ◽  
pp. 358-375 ◽  
Author(s):  
Veronica Baldo ◽  
Valentina Testoni ◽  
Giovanna Lucchini ◽  
Maria Pia Longhese
Keyword(s):  
Dna Damage ◽  
Protein Kinases ◽  
Dna Lesions ◽  
Wild Type ◽  
Checkpoint Activation ◽  
Telomere Shortening ◽  
Checkpoint Response ◽  
Double Stranded Dna ◽  
Telomere Homeostasis

ABSTRACT Eukaryotic genome integrity is safeguarded by two highly conserved protein kinases that are called ATR and ATM for humans and Mec1 and Tel1 for Saccharomyces cerevisiae. Although they share sequence similarities and substrates, these protein kinases perform different specialized functions. In particular, Mec1 plays a key role in the DNA damage checkpoint response, whereas Tel1 primarily is involved in telomere homeostasis, and its checkpoint function is masked by the prevailing activity of Mec1. In order to understand how this specificity is achieved, we searched for TEL1 mutations able to compensate for the lack of Mec1 functions. Here, we describe seven independent dominant TEL1-hy alleles that are able to suppress, to different extents, both the hypersensitivity to genotoxic agents and the checkpoint defects of Mec1-deficient cells. Most of these alleles also cause telomere overelongation. In vitro kinase activity was increased compared to that of wild-type Tel1 in the Tel1-hy385, Tel1-hy394, Tel1-hy680, and Tel1-hy909 variants, but its activity was not affected by the TEL1-hy184 and TEL1-hy628 mutations and was slightly reduced by the TEL1-hy544 mutation. Thus, the phenotypes caused by at least some Tel1-hy variants are not simply the consequence of improved catalytic activity. Further characterization shows that Tel1-hy909 not only can sense and signal a single double-stranded DNA break, unlike wild-type Tel1, but also contributes more efficiently than Tel1 to single-stranded DNA accumulation at double-strand ends, thus enhancing Mec1 signaling activity. Moreover, it causes unscheduled checkpoint activation in unperturbed conditions and upregulates the checkpoint response to small amounts of DNA lesions. Finally, Tel1-hy544 can activate the checkpoint more efficiently than wild-type Tel1, while it causes telomere shortening, indicating that the checkpoint and telomeric functions of Tel1 can be separable.

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