Direct measurements of the binding between light-activated rhodopsin (Rho*) and transducin, the retinal rod G-protein, revealed a strongly cooperative interaction. Cooperativity was assessed by measuring the association of 125I-labeled transducin (Gt) to Rho* in urea-stripped rod outer segment membranes at equilibrium. Analysis of 125I-Gt binding curves gave a Hill coefficient of 1.8. These dat...

A technique is described to measure a surface self-diffusion coefficient (D) of a metal (gold) by scanning tunneling microscopy. Micro-hills formed on a gold face show a shape evolution by a diffusion transport of kink site atoms. D is determined via a measurement of the hill apex radius as a function of time and includes corrections of image errors. The technique shows that STM can be used to ...

Binary descriptors of image patches provide processing speed advantages and require less storage than methods that encode the patch appearance with a vector of real numbers. We provide evidence that, despite its simplicity, a stochastic hill climbing descriptor construction process defeats recently proposed alternatives on a standard discriminative power benchmark. The method is easy to impleme...

We build new algebraic structures, which we call genuine equivariant operads, can be thought of as a hybrid between operads and coefficient systems. then prove an Elmendorf-Piacenza type theorem stating that with their graph model structure, are equivalent to projective structure. As application, explicit models for the $N_{\infty}$-operads Blumberg Hill.

In this paper, we investigate the temperature and pH dependence of the mitochondrial inner membrane anion channel (IMAC) that is believed to be involved in mitochondrial volume homeostasis. At pH 7. 4, the flux of malonate is highly temperature-dependent with rates increasing from 1 nmol/min mg at 5 degrees C to 1900 nmol/min mg at 45 degrees C. The Arrhenius plot is nonlinear with the activati...

Cellular Na+/H+ exchanger (NHE) activity is elevated in type 1 diabetic patients with nephropathy and patients with essential hypertension. The characteristics of this NHE phenotype in hypertension (raised Vmax and a lowered Hill coefficient) are preserved in Epstein-Barr virus-transformed lymphoblasts from hypertensive patients. In this study, we have determined NHE kinetics in cultured lympho...

Inducible expression systems are widely employed for the titratable control of gene expression, yet molecules inadvertently present in the growth medium or synthesized by the host cells can alter the response profile of some of these systems. Here, we explored the quantitative impact of these residual inducers on the apparent response properties of inducible systems. Using a simple mathematical...

Phenyldiazene reacted with lymphoblast-expressed CYP3A4 to give a stable phenyl-iron complex that could be induced to rearrange in situ producing approximately equal amounts of four N-phenyl-protoporphyrin IX isomers (N(B):N(A):N(C):N(D), 01:01:02:02). In the presence of 10 mM MgCl(2), the formation profile of the protoporphyrin isomers was markedly altered compared with control, favoring the N...

Biological signal transduction commonly involves cooperative interactions in the binding of ligands to their receptors. In many cases, ligand concentrations in vivo are close to the value of the dissociation constant of their receptors, resulting in the phenomenon of ligand depletion. Using examples based on rotational bias of bacterial flagellar motors and calcium binding to mammalian calmodul...

The end product of human purine metabolism is urate, which is produced primarily in the liver and excreted by the kidney through a well-defined basolateral blood-to-cell uptake step. However, the apical cell-to-urine efflux mechanism is as yet unidentified. Here, we show that the renal apical organic anion efflux transporter human multidrug resistance protein 4 (MRP4), but not apical MRP2, medi...