CAMP-Dependent PKA: A Synthesis

Phosphodiesterase breaks phosphodiester bond and converts cAMP back to AMP, getting rid of second messenger

ULK1 was also tested in vitro in order to determine it could serve as a direct AMPK substrate. A kinase inactive kinase allele was made to remove autophosphorylation properties that ULK1 may have. Also, ULK1 phosphorylation by AMPK was compared to raptor – an established substrate. In addition, the group also created phosphospecific antibodies that acted against Ser 467 and Ser 555. This was done in order to understand phosphorylation under the absence of energy stress.

Changes in the concentration of small molecules, called second messengers, constitute the next step in the molecular information circuit. Particularly important second messengers include cyclic AMP and cyclic GMP, calcium ion, inositol 1,4,5-trisphosphate, (IP3), and diacylglycerol. The use of second messengers has several consequences. First, second messengers are often free to diffuse to other compartments of the cell, such as the nucleus, where they can influence gene expression and other processes. Second, the signal may be amplified significantly in the generation of second messengers. Enzymes or membrane channels are almost always activated in second-messenger generation; each activated macromolecule can lead to the generation of many second messengers within the cell. Thus, a low concentration of the signal in the environment, even as little as a single molecule, can yield a large intracellular signal and response. Third, the use of common second messengers in multiple signaling pathways creates both opportunities and possible problems. Input from several signaling pathways, often called cross talk, may affect the concentrations of common second messengers. Cross talk permits more finely tuned regulation of cell activity than would the action of individual independent pathways. However, unsuitable cross talk can cause second messengers to be

consists of ComP, the histidine kinase, and ComA, the response regulator.2 There are two known

Phosphodiesterases (PDEs) are a class of enzymes, which are responsible for the breakdown of phosphodiester bonds, specifically hydrolysing cyclic nucleotides, like the secondary messenger molecules cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) in the striatal region of the brain.1 Via their control of both cAMP and cGMP in the cell, PDEs contribute to cell signalling making them potentially important drug targets.2 This enzyme class consists of 11 different families, PDE1 to PDE11, which vary in sequence homology, domain architecture and sequence homology.1 PDE10A is a PDE of current interest as a possible target to treat neurological diseases such as Schizophrenia and

The nucleotide binding domain of CFTR contains many conserved motifs found in many other ABC proteins. One of these motifs, the Walker A motif, is the catalytic binding site for ATP. A nearby parallel β-sheet also contains a conserved motif, the Walker B motif. Another motif, important

The active site on ACs are not the only place molecules can bind. Beyond the active site lies a Forskolin (FS) binding site. FS is a diterpene molecule that when bound to AC raises cAMP levels.5 FS binds to a hydrophobic pocket on the other side of the groove that the active site sits in. As previously mentioned, FS stimulates AC isoforms 1-8, but AC9 is largely insensitive to its binding, which raises questions as to the evolutionary purpose of this domain being conserved across all isoforms save one.

GPCR desensitization is a deactivation of GPCR-elicited signaling following prolonged or repeated agonist exposure. A major mechanism underlying desensitization is agonist-stimulated phosphorylation and endocytosis of the receptor. The second messenger-dependent protein kinases were originally regarded as the principal mediators of GPCR phosphorylation and desensitization. However, following the discovery of G protein-coupled receptor kinases (GRKs, originally called -adrenoceptor kinases), the GRKs have been shown to play a central role in the agonist-induced desensitization of many GPCRs (Kelly 2008). The GRK family of serine/threonine kinases comprises seven members. Based on sequence homology, vertebrate

This does not confirm that the two proteins are indeed interacting with one another. This experiment also does not guarantee that it is the activation of PLCγ1 that is causing this interaction. Additional experiments measuring the concentration of Ca2+ and dicylglycerol in the cytosol would be necessary to confirm the activation PLCγ1. This can be done via fluorescent microscopy and stain that can detect calcium, this could be compared to an image of a negative control where the PLCγ1 is disabled. The proximity of fascin and PKCγ can be determined by further analysis using FRET (fluorescence resonance energy transfer) analysis. Each protein would have to be transfected with a proper marker that would produce a detectable light energy transfer. The greater the FRET efficiency, the closer the two proteins are together. A control using the K380A mutant, would measure the baseline FRET efficiency of the MDA-MB-231 cells an increase in this efficiency would indicate that the two proteins have indeed gotten much closer

consequently the stopping of the synthesis of the ATP, thus a decrease in the contractile

The PI3Ks are linked to variety of different signaling pathways, but each version of the lipid enzyme has a similar PIK core region [2]. This region of the PI3K is composed of three essential parts: a C2 region, a helical region, and a catalytic region; it should be noted that in some forms of the PI3Ks these regions are split up on different subunits (refer to Figure 1 below) [2]. From these three structural components, the PI3K is able to carry out its important activating role and create the three products listed above. These products are noted to remain near the plasma membrane- on the cytosolic side- and to have their own biding sites [3]. The binding sites on the PI3K products are indications of the signaling pathway, and therefore attract other signaling proteins, like the serine-threonine kinases PKB and PDK1 [3]. It is also important to mention that the PI3K signal and its products can both be terminated by removing the phosphate added to the inositol ring of the phosphoinositide; this is done by the lipid phosphatase known as PTEN [3]. A termination step is important in the regulating activity of PI3Ks, and therefore in regulating the activities of the cell. From the medical field perspective, PI3Ks are important since they are linked to crucial pathways for insulin regulation and cell growth.

Phosphodiesterases (PDEs) act on cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). PDE5 plays a role in the smooth muscle cells of the bladder, and the endothelium of blood vessels.(6) PDE5 has been shown to have the highest expression in the muscular cells in the lower urinary tract.(7) Truss was the first to demonstrate the presence of PDE 1, 2, 3, 4 and 5 isoenzymes in the human detrusor. (8) PDE5 affects cAMP and cGMP which alters the intracellular calcium concentration [Ca], which is the primary regulator of smooth muscle contractility.

Sphingosine 1-phosphate, a product of sphingosine kinases (SphK), mediates various biological processes including cell proliferation, differentiation, motility, and apoptosis. Protein kinase C (PKC), is a family of protein kinase enzymes involved in controlling the function of other proteins through the phosphorylation of hydroxyl groups of serine and threonine amino acid residues.

Another genetic mutation identified is the ABCA3 mutation. It has been demonstrated that this mutation is more common than SP-B deficiency (Somaschini et al., 2007) This gene encodes the ATP-binding cassette protein A3. The protein is highly

IKBKB gene encoding the IkB kinase which plays an essential role in NFkB signalling pathway, it has kinase activity which phosphorylate the inhibitor of NFkB and targeting it for degradation, detail are shown as below.