Parshuram Rath

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Phospholamban is a 52-amino acid residue membrane protein that regulates Ca(2+)-ATPase activity in the sarcoplasmic reticulum of cardiac muscle cells. The hydrophobic C-terminal 28 amino acid fragment of phospholamban (hPLB) anchors the protein in the membrane and may form part of a Ca(2+)-selective ion channel. We have used polarized attenuated total(More)
The M-->N transition in the photocycle of bacteriorhodopsin involves the transfer of a proton from Asp96 to the retinylidene Schiff base, possibly through a network of hydrogen-bonded amino acid residues and water molecules (Rothschild, K. J., He, Y. W., Sonar, S., Marti, T., and Khorana, H. G. (1992) J. Biol. Chem. 267, 1615-1622). A conformational change(More)
To determine the effect of Sodium N-[8-(2-hydroxybenzoyl)amino]caprylate (SNAC) on the permeation of cromolyn across Caco-2 cell monolayers and explore the molecular basis for the enhanced absorption. Transport studies of cromolyn across Caco-2 cell monolayers were conducted in the presence of various SNAC concentrations. Permeation of cellular transport(More)
A question of fundamental importance concerning the biosynthesis of integral membrane proteins is whether transmembrane secondary structure can insert spontaneously into a lipid bilayer. It has proven to be difficult to address this issue experimentally because of the poor solubility in aqueous solution of peptides and proteins containing these extremely(More)
A key step in visual transduction is the light-induced conformational changes of rhodopsin that lead to binding and activation of the G-protein transducin. In order to explore the nature of these conformational changes, time-resolved Fourier transform infrared spectroscopy was used to measure the kinetics of hydrogen/deuterium exchange in rhodopsin upon(More)
The bacteriorhodopsin (bR) mutants Asp-85-->Asn (D85N) and Asp-85-->Ala (D85A) have a red-shifted chromophore absorption and exhibit no proton pumping (Otto, H., Marti, T., Holz, M., Mogi, T., Stern, L., Engel, F., Khorana, H. G., and Heyn, M. P. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 1018-1022) consistent with the hypothesis that Asp-85 functions as a(More)
Both sensory rhodopsin I, a phototaxis receptor, and bacteriorhodopsin, a light-driven proton pump, have homologous residues which have been identified as critical for bacteriorhodopsin functioning. This includes Asp76, which in the case of bacteriorhodopsin (Asp85) functions as both the Schiff base counterion and the proton acceptor. Sensory rhodopsin I(More)
Fourier transform infrared (FTIR) difference spectroscopy and site-directed mutagenesis have been used to investigate structural changes which occur during rhodopsin photoactivation at the level of individual amino acid residues. The rhodopsin-->bathorhodopsin FTIR difference spectra of the mutants Asp-83-->Asn (D83N) and Glu-134-->Asp (E134D) incorporated(More)
A question of fundamental importance concerning the biosynthesis of integral membrane proteins is whether transmembrane secondary structure can insert spontaneously into a lipid bilayer. It has proven to be difficult to address this issue experimentally because of the poor solubility in aqueous solution of peptides and proteins containing these extremely(More)
FTIR difference spectroscopy has been used to study the role of cysteine residues in the photoactivation of rhodopsin. A positive band near 2550 cm-1 with a low frequency shoulder is detected during rhodopsin photobleaching, which is assigned on the basis of its frequency and isotope shift to the S-H stretching mode of one or more cysteine residues.(More)