Photodynamic Oxidation of Iodide Ion by Anthracene Sulphonates

723-72

Hedgehog-Regulated Ubiquitination Controls Smoothened Trafficking and Cell Surface Expression in Drosophila

Hedgehog transduces signal by promoting cell surface expression of the seven-transmembrane protein Smoothened (Smo) in Drosophila, but the underlying mechanism remains unknown. Here we demonstrate that Smo is downregulated by ubiquitin-mediated endocytosis and degradation, and that Hh increases Smo cell surface expression by inhibiting its ubiquitination. We find that Smo is ubiquitinated at multiple Lysine residues including those in its autoinhibitory domain (SAID), leading to endocytosis and degradation of Smo by both lysosome- and proteasome-dependent mechanisms. Hh inhibits Smo ubiquitination via PKA/CK1-mediated phosphorylation of SAID, leading to Smo cell surface accumulation. Inactivation of the ubiquitin activating enzyme Uba1 or perturbation of multiple components of the endocytic machinery leads to Smo accumulation and Hh pathway activation. In addition, we find that the non-visual β-arrestin Kurtz (Krz) interacts with Smo and acts in parallel with ubiquitination to downregulate Smo. Finally, we show that Smo ubiquitination is counteracted by the deubiquitinating enzyme UBPY/USP8. Gain and loss of UBPY lead to reciprocal changes in Smo cell surface expression. Taken together, our results suggest that ubiquitination plays a key role in the downregulation of Smo to keep Hh pathway activity off in the absence of the ligand, and that Hh-induced phosphorylation promotes Smo cell surface accumulation by inhibiting its ubiquitination, which contributes to Hh pathway activation

Some aspects of photophysics of dyes and self-aggregation phenomenon in solution

500-51

Energy Transfer between Dye Molecules Having Overlapping Absorption Bands: Kinetics of Quenching of Fluorescence of Fluorescene by Rose Bengal

729-73

Flash Photolysis Study of Phenosafranine-EDTA System

623-62

Flash Photolysis Study of Photosensitized Oxidation of Iodide Ion by Anthracene Sulphonates

332-33

Substituent Perturbation on Masked 1Lb-1A1 Transition of Anthracene Monosulphonates: Detection by Photoselection in Glycerol Glass at 77K

186-19

Triplet state interaction of phenosafranine with inorganic cations

569-574The quenching of triplet state of phenosafranine (PSF) dye by Fe2+, Mn2+ and CO2+ has been studied at pH 4.5. The doubly protonated long-lived triplet species 3DH absorbs at 620 nm whereas the radical ion DH absorbs at 660 nm. First order decay kinetics are observed which appear to change to second order at later decay times in the quenching process. In the presence of low [quencher], the decay.-rate can be fitted to the first order kinetic expression. The interaction of 3PSF with the quencher ions generates reduced semi-dye by electron transfer-mechanism. The reduction of 3PSF by Mn2+and Fe2+ is thermodynamically allowed but electron transfer from CO2+ to 3PSF is endoergic. The mechanism of quenching by CO2+ can be visualised as complexation by charge transfer mechanism between 3PSF and CO2+ which can lead to enhancement of the spin forbidden radiationless processes

Cyclic Voltammetric Study of Reduction of Phenosafranine by EDTA

630-63