the ds-rna activated protein kinase (pkr) is a serine-threonine kinase with mw of 68 kda. it belongs to a family of kinases that control one of the translational initiation factors, eif2. pkr is produced at high level in response to viral infection. this protein by phosphorylating eif2 inhibits cellular protein synthesis. in this study, the effect of gamma interferon (ifn-γ), an activator, and ...

The trout red blood cell Na+/H+ antiporter (beta NHE) plays two interesting properties: it is the only NHE own to be activated by cyclic AMP, and the activation process is followed by a desensitisation of the transport system itself. Cloning and expression of beta NHE have provided inificant information about Na+/H+ activation, in particular that activation by cyclic AMP is directly dependent u...

Aggressive melanoma cells can engage in a process termed vasculogenic mimicry (VM) that reflects the ability of tumor cells to express a multipotent, stem cell-like phenotype. Melanoma cell plasticity contributes to the lack of efficient therapeutic strategies targeting metastatic tumors. This study reveals cyclic AMP as a mediator of VM in vitro. In uveal and cutaneous metastatic aggressive hu...

AMP-activated protein kinase (AMPK) is a sensor of energy status that maintains cellular energy homeostasis. It arose very early during eukaryotic evolution, and its ancestral role may have been in the response to starvation. Recent work shows that the kinase is activated by increases not only in AMP, but also in ADP. Although best known for its effects on metabolism, AMPK has many other functi...

Glutamate, as an essential neurotransmitter, has been thought to have different roles in the central nervous system (CNS), including nerve regeneration, synaptogenesis, and neurogenesis. Excessive glutamate causes an up-regulation of the multiple signaling pathways, including phosphoinositide-3 kinase/protein kinase B (PI3K/Akt), Akt/mammalian target of rapamycin (mTOR) protein, mitogen-activat...

Activation of AMPK (AMP-activated protein kinase) by phosphorylation at Thr172 is catalysed by at least two distinct upstream kinases, i.e. the tumour suppressor LKB1, and CaMKKbeta (Ca2+/calmodulin-dependent protein kinase kinase-beta). The sequence around Thr172 is highly conserved between the two catalytic subunit isoforms of AMPK and the 12 AMPK-related kinases, and LKB1 has been shown to a...

The AMP-activated protein kinase is a metabolic regulator that transduces information about energy and nutrient availability. In yeast, the AMP-activated protein kinase, called Snf1, is activated when energy and nutrients are scarce. Earlier studies have demonstrated that activation of Snf1 requires the phosphorylation of the activation loop on threonine 210. Here we examined the regulation of ...

Three functionally related components that block peptide initiation have been identified in lysates of rabbit reticulocytes. The components function consecutively in a cascade type sequence of reactions to cause phosphorylation of eukaryotic peptide initiation factor 2 (eIF-2). The eIF-2 kinase activated as part of this sequence has been tentatively identified as the same protein kinase that is...

We report that sphingosine and short-chain ceramides activate adenylate cyclase and stimulate intracellular cyclic AMP formation in airway-smooth-muscle (ASM) cells. In each case, there is a conditional requirement for GTP-Gs alpha. Sphingosine utilizes a protein kinase C-dependent pathway to elicit activation of adenylate cyclase, whereas for short-chain ceramides the mechanism remains unident...