ATP:Co(I)rrinoid adenosyltransferase (ACA) catalyzes the conversion of cobalamin to coenzyme B12, an essential cofactor in animal metabolism. Several mutations of conserved residues in the active site of human ACA have been identified in humans with methylmalonic aciduria. However, the catalytic role of these residues remains unclear. To better understand the function of these residues and to d...

ATP-sensitive K(+) (K(ATP)) channels are composed of pore-forming subunits (Kir6.x) and of regulatory subunits, the sulfonylurea receptors (SURx). Subtypes of K(ATP) channels are expressed in different organs. The sulfonylureas and glinides (insulinotropes) close the K(ATP) channel in pancreatic beta-cells and stimulate insulin secretion. The insulinotrope binding site of the pancreatic channel...

Regulation by cytosolic nucleotides of Ca2+- and ATP-sensitive nonselective cation channels (CA-NSCs) in rat brain capillary endothelial cells was studied in excised inside-out patches. Open probability (Po) was suppressed by cytosolic nucleotides with apparent KI values of 17, 9, and 2 microM for ATP, ADP, and AMP, as a consequence of high-affinity inhibition of channel opening rate and low-af...

P2X receptors are ATP-gated non-selective cation channels involved in many different physiological processes, such as synaptic transmission, inflammation, and neuropathic pain. They form homo- or heterotrimeric complexes and contain three ATP-binding sites in their extracellular domain. The recent determination of X-ray structures of a P2X receptor solved in two states, a resting closed state a...

FtsE and FtsX of Escherichia coli constitute an apparent ABC transporter that localizes to the septal ring. In the absence of FtsEX, cells divide poorly and several membrane proteins essential for cell division are largely absent from the septal ring, including FtsK, FtsQ, FtsI, and FtsN. These observations, together with the fact that ftsE and ftsX are cotranscribed with ftsY, which helps to t...

Kinetic studies of the reactions catalyzed by herpes simplex virus type l-encoded thymidine and thymidylate multifunctional kinase indicate that the addition of substrates (thymidine and ATP*Mg’+, or thymidylate and ATP l Mg2+) to the enzyme is random, while release of the products (thymidylate and ADP*M8+, or thymidine diphosphate and ADP*Mg+) is ordered, with ADP.Mg2+ being released first. Th...

Cystic fibrosis transmembrane conductance regulator (CFTR), a member of the ABC (ATP binding cassette) transporter family, is a chloride channel whose activity is controlled by protein kinase-dependent phosphorylation. Opening and closing (gating) of the phosphorylated CFTR is coupled to ATP binding and hydrolysis at CFTR's two nucleotide binding domains (NBD1 and NBD2). Recent studies present ...

Plasmodium falciparum (P. falciparum) is the main parasite known to cause malaria in humans. The antimalarial drug atovaquone inhibit Qo-site of cytochrome bc1 complex P. falciparum, which ultimately blocks ATP synthesis, leading cell death. Through years, mutations complex, causing resistance atovaquone, have emerged. present investigation applies molecular dynamics (MD) simulations study how ...

A DNA fragment containing the minute virus of mice 3' replication origin was specifically coprecipitated in immune complexes containing the virally coded NS1, but not the NS2, polypeptide. Antibodies directed against the amino- or carboxy-terminal regions of NS1 precipitated the NS1-origin complexes, but antibodies directed against NS1 amino acids 284 to 459 blocked complex formation. Using aff...

The structures of both monomeric and dimeric yeast hexokinase complexed with sugar and nucleotide substrates and analogues have been determined at 3.5 to 2.7 b resolution. The most striking finding is that there are two kinds of nucleotide binding sites in the dimeric enzyme. We conclude that one kind of site, the A site, binds the ATP involved in the kinase reaction while the other site, the I...