University of Texas Southwestern Medical Center

About: University of Texas Southwestern Medical Center is a healthcare organization based out in Dallas, Texas, United States. It is known for research contribution in the topics: Population & Cancer. The organization has 39107 authors who have published 75242 publications receiving 4497256 citations. The organization is also known as: UT Southwestern & UT Southwestern Medical School.

Regulation of bacterial gene expression by riboswitches

Abstract: Riboswitches are structured domains that usually reside in the noncoding regions of mRNAs, where they bind metabolites and control gene expression. Like their protein counterparts, these RNA gene control elements form highly specific binding pockets for the target metabolite and undergo allosteric changes in structure. Numerous classes of riboswitches are present in bacteria and they comprise a common and robust metabolite-sensing system.

Endothelin System: The Double-Edged Sword in Health and Disease

Abstract: The endothelin system consists of two G-protein-coupled receptors, three peptide ligands, and two activating peptidases. Its pharmacological complexity is reflected by the diverse expression patter...

Prosthetic heart valves

Abstract: Since the 1950s more than 80 models of prosthetic heart valves have been developed and used. More than 60,000 valve replacements are performed annually in the United States. Prosthetic heart valves may be mechanical or bioprosthetic. Mechanical valves, which are composed primarily of metal or carbon alloys, are classified according to their structure as caged-ball, single-tilting-disk, or bileaflet-tilting-disk valves. Bioprostheses may be heterografts, which are composed of porcine or bovine tissue (pericardial or valvular) mounted on a metal support, or homografts, which are preserved human aortic valves. The most commonly used prosthetic valves are listed in Table 1 and illustrated in Figure 1. . . .

A conformational switch in syntaxin during exocytosis: role of munc18

Abstract: Syntaxin 1, an essential protein in synaptic membrane fusion, contains a helical autonomously folded N-terminal domain, a C-terminal SNARE motif and a transmembrane region. The SNARE motif binds to synaptobrevin and SNAP-25 to assemble the core complex, whereas almost the entire cytoplasmic sequence participates in a complex with munc18-1, a neuronal Sec1 homolog. We now demonstrate by NMR spectroscopy that, in isolation, syntaxin adopts a 'closed' conformation. This default conformation of syntaxin is incompatible with core complex assembly which requires an 'open' syntaxin conformation. Using site-directed mutagenesis, we find that disruption of the closed conformation abolishes the ability of syntaxin to bind to munc18-1 and to inhibit secretion in PC12 cells. These results indicate that syntaxin binds to munc18-1 in a closed conformation and suggest that this conformation represents an essential intermediate in exocytosis. Our data suggest a model whereby, during exocytosis, syntaxin undergoes a large conformational switch that mediates the transition between the syntaxin-munc18-1 complex and the core complex.