The range of ATP concentrations that can be measured with a fluorescent reagentless biosensor for ATP has been increased by modulating its affinity for this analyte. The ATP biosensor is an adduct of two tetramethylrhodamines with MatB from Rhodopseudomonas palustris. Mutations were introduced into the binding site to modify ATP binding affinity, while aiming to maintain the concomitant fluores...

The binding and conformational properties of the divalent cation site required for H+,K(+)-ATPase catalysis have been explored by using Ca2+ as a substitute for Mg2+. 45Ca2+ binding was measured with either a filtration assay or by passage over Dowex cation exchange columns on ice. In the absence of ATP, Ca2+ was bound in a saturating fashion with a stoichiometry of 0.9 mol of Ca2+ per active s...

TRPV1 plays a key role in nociception, as it is activated by heat, low pH, and ligands such as capsaicin, leading to a burning pain sensation. We describe the structure of the cytosolic ankyrin repeat domain (ARD) of TRPV1 and identify a multiligand-binding site important in regulating channel sensitivity within the TRPV1-ARD. The structure reveals a binding site that accommodates triphosphate ...

Hsp90 molecular chaperones in eukaryotic cells play essential roles in the folding and activation of a range of client proteins involved in cell cycle regulation, steroid hormone responsiveness, and signal transduction. The biochemical mechanism of Hsp90 is poorly understood, and the involvement of ATP in particular is controversial. Crystal structures of complexes between the N-terminal domain...

ABC exporters pump substrates across the membrane by coupling ATP-driven movements of nucleotide binding domains (NBDs) to the transmembrane domains (TMDs), which switch between inward- and outward-facing (IF, OF) orientations. DEER measurements on the heterodimeric ABC exporter TM287/288 from Thermotoga maritima, which contains a non-canonical ATP binding site, revealed that in the presence of...

Substrate (or solute)-binding proteins (SBPs) selectively bind the target ligands and deliver them to ATP-binding cassette (ABC) transport system for their translocation. Irrespective of different types ligands, SBPs are structurally conserved. A wealth structural details bound physiological basis import available; however, uptake mechanism nucleotides is still deficient. In this study, we eluc...

In this work, we demonstrate that the phosphatidylinositol 3,4,5-trisphosphate-binding protein JFC1 is an ATP-binding protein with magnesium-dependent ATPase activity. We show that JFC1 specifically binds to the ATP analog 8-azido-[alpha-(32)P]ATP. The affinity of JFC1 for [alpha-(32)P]ATP was 10x greater than its affinity for [alpha-(32)P]ADP; the protein did not appear to bind to [alpha-(32)P...