Activation of the P2X7 ion channel by soluble and covalently bound ligands

The homotrimeric P2X7 purinergic receptor has sparked interest because of its capacity to sense adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide (NAD) released from cells and to induce calcium signaling and cell death. Here, we examine the response of arginine mutants of P2X7 to soluble and covalently bound ligands. High concentrations of ecto-ATP gate P2X7 by acting as a soluble ligand and low concentrations of ecto-NAD gate P2X7 following ADP-ribosylation at R125 catalyzed by toxin-related ecto-ADP-ribosyltransferase ART2.2. R125 lies on a prominent cysteine-rich finger at the interface of adjacent receptor subunits, and ADP-ribosylation at this site likely places the common adenine nucleotide moiety into the ligand-binding pocket of P2X7

An Environment Adaptive Practical Packet Scheduling Algorithm with Single User Fairness Guarantee over the Forward Link of 3G Cellular Data Services

Aluminum castings can contain pinholes caused by porosity from a number of sources, including the presence of gas or from shrinkage. These pinholes, although normally small in size and number, can greatly influence the properties of the casting, often resulting in the scrapping of the part. While many factors are involved in the formation of porosity in aluminum castings, such as the influences of hydrogen and aluminum oxide (A12O3) on gas-porosity, this study investigates the effects of cooling rate and section thickness. These factors are studied by using a sand cast aluminum bar with different section thicknesses which undergo different cooling rates during casting [1,2]