Selectivity and Cooperativity of Modulatory Ions in a Neurotransmitter Receptor

Ions play a modulatory role in many proteins. Kainate receptors, members of the ionotropic glutamate receptor family, require both monovalent anions and cations in the extracellular milieu for normal channel activity. Molecular dynamics simulations and extensive relative binding free energy calculations using thermodynamic integration were performed to elucidate the rank order of binding of monovalent cations, using x-ray crystal structures of the GluR5 kainate receptor dimers with bound cations from the alkali metal family. The simulations show good agreement with experiments and reveal that the underlying backbone structure of the binding site is one of the most rigid regions of the protein. A simplified model where the partial charge of coordinating oxygens was varied suggests that selectivity arises from the presence of two carboxylate groups. Furthermore, using a potential of mean force derived from umbrella sampling, we show that the presence of cations lower the energy barrier for anion approach and binding in the buried anion binding cavity

Kinesiological Factors in Vertical Jump Performance: Differences Among Individuals

The purpose of this study was to investigate the kinesiological factors that distinguish good jumpers from poor ones, in an attempt to understand the critical factors in vertical jump performance (VJP). Fifty-two normal, physically active male college students each performed five maximal vertical jumps with arms akimbo. Ground reaction forces and video data were collected during the jumps. Subjects' strength was tested isometrically. Thirty-five potential predictor variables were calculated for statistical modeling by multiple-regression analysis. At the whole-body level of analysis, the best models (which included peak and average mechanical power) accounted for 88% of VJP variation (p < .0005). At the segmental level, the best models accounted for 60% of variation in VJP (p < .0005). Unexpectedly, coordination variables were not related to VJP. These data suggested that VJP was most strongly associated with the mechanical power developed during jump execution.The University of Michigan/[Rackham Predoctoral Fellowship]//Estados UniddosThe University of Michigan/[Rackham Dissertation Grant]//Estados UnidosUCR::Vicerrectoría de Docencia::Ciencias Sociales::Facultad de Educación::Escuela de Educación Físic