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Articles 1 - 4 of 4
Full-Text Articles in Physical Sciences and Mathematics
36 Degrees Step Size Of Proton-Driven C-Ring Rotation In Fof1-Atp Synthase, Monika Düser, Nawid Zarrabi, Daniel Cipriano, Stefan Ernst, Gary Glick, Stanley Dunn, Michael Börsch
36 Degrees Step Size Of Proton-Driven C-Ring Rotation In Fof1-Atp Synthase, Monika Düser, Nawid Zarrabi, Daniel Cipriano, Stefan Ernst, Gary Glick, Stanley Dunn, Michael Börsch
Stanley D Dunn
Synthesis of adenosine triphosphate ATP, the 'biological energy currency', is accomplished by F(o)F(1)-ATP synthase. In the plasma membrane of Escherichia coli, proton-driven rotation of a ring of 10 c subunits in the F(o) motor powers catalysis in the F(1) motor. Although F(1) uses 120 degrees stepping during ATP synthesis, models of F(o) predict either an incremental rotation of c subunits in 36 degrees steps or larger step sizes comprising several fast substeps. Using single-molecule fluorescence resonance energy transfer, we provide the first experimental determination of a 36 degrees sequential stepping mode of the c-ring during ATP synthesis.
Re-Introduction Of Transmembrane Serine Residues Reduce The Minimum Pore Diameter Of Channelrhodopsin-2, Robert Dempski, Ryan Richards
Re-Introduction Of Transmembrane Serine Residues Reduce The Minimum Pore Diameter Of Channelrhodopsin-2, Robert Dempski, Ryan Richards
Robert E. Dempski
Channelrhodopsin-2 (ChR2) is a microbial-type rhodopsin found in the green algae Chlamydomonas reinhardtii. Under physiological conditions, ChR2 is an inwardly rectifying cation channel that permeates a wide range of mono- and divalent cations. Although this protein shares a high sequence homology with other microbial-type rhodopsins, which are ion pumps, ChR2 is an ion channel. A sequence alignment of ChR2 with bacteriorhodopsin, a proton pump, reveals that ChR2 lacks specific motifs and residues, such as serine and threonine, known to contribute to non-covalent interactions within transmembrane domains. We hypothesized that reintroduction of the eight transmembrane serine residues present in bacteriorhodopsin, but …
Structural Insights Into Neuronal K+ Channel-Calmodulin Complexes, Karen Mruk, Shivender Shandilya, Robert Blaustein, Celia Schiffer, William Kobertz
Structural Insights Into Neuronal K+ Channel-Calmodulin Complexes, Karen Mruk, Shivender Shandilya, Robert Blaustein, Celia Schiffer, William Kobertz
Celia A. Schiffer
Calmodulin (CaM) is a ubiquitous intracellular calcium sensor that directly binds to and modulates a wide variety of ion channels. Despite the large repository of high-resolution structures of CaM bound to peptide fragments derived from ion channels, there is no structural information about CaM bound to a fully folded ion channel at the plasma membrane. To determine the location of CaM docked to a functioning KCNQ K(+) channel, we developed an intracellular tethered blocker approach to measure distances between CaM residues and the ion-conducting pathway. Combining these distance restraints with structural bioinformatics, we generated an archetypal quaternary structural model of …
The Molecular Determinants Of The Zinc Transporter, Hzip4, Robert Dempski, Sagar Antala, Tuong-Vi Nguyen
The Molecular Determinants Of The Zinc Transporter, Hzip4, Robert Dempski, Sagar Antala, Tuong-Vi Nguyen
Robert E. Dempski
Zinc is an essential micronutrient which is required for the function of hundreds of cellular enzymes. In addition, zinc is the second most abundant transition metal found in biological systems (iron is most abundant). However, the concentration of free zinc is nano to picomolar since most zinc is bound to proteins. This makes investigating the mechanism of zinc transport across the plasma membrane a challenge. Our interest has been to elucidate the mechanism of zinc transport mediated by one member of the ZIP family of proteins, hZIP4.