The change in electrical conductance of rhodopsin solutions was studied with flash-photolysis techniques. The whole pattern of the conductance change on illumination consists of three different processes: (I) the initial decrease, (II) the increase, and (III) the slow decrease, which are in decreasing order of reaction rate. The processes I, II, and III can be most distinctly recognized on flas...

A pH-sensitive site controls the lambda max of Limulus metarhodopsin. The properties of this site were examined using intracellular recordings of the early receptor potential (ERP) as a pigment assay. ERPs recorded over a range of extracellular pHs indicate that the apparent pK of the site is in the range of 8.3-8.6. Several lines of evidence indicate that the site responds directly to changes ...

A B S X R A C T A pH-sensitive site controls the Amax of Limulus metarhodopsin. The properties of this site were examined using intracellular recordings of the early receptor potential (ERP) as a pigment assay. ERPs recorded over a range of extracellular pHs indicate that the apparent pK of the site is in the range of 8.3-8.6. Several lines of evidence indicate that the site responds directly t...

A a ST RA C T Individual , isolated rhabdoms from dark-adapted crayfish (Orconectes, Procambarus) were studied with a laterally incident microbeam that could be placed in single stacks o f microvilli. Concentrat ion gradients of metarhodopsin along the lengths of microvilli were produced by local bleaches, accomplished by irradiat ion with small spots of orange light at pH 9 in the presence of ...

Arrestin was identified in ciliary photoreceptors of Pecten irradians, and its role in terminating the light response was established electrophysiologically. Downstream effectors in these unusual visual cells diverge from both microvillar photoreceptors and rods and cones; the finding that key regulatory mechanisms of the early steps of visual excitation are conserved across such distant lineag...

PURPOSE To take advantage of specialized microscopic methods and transgenic stocks, to understand the properties of each rhodopsin now that Drosophila's six rhodopsins (Rh1-Rh6) have been isolated. METHODS The visual pigment containing organelles, the rhabdomeres, were imaged in live flies with the pseudopupil in standard and confocal microscopes. Five transgenic Drosophila strains in which R...

Three aspects of protein-phospholipid-cholesterol interaction in microvillar membranes of octopus photoreceptor cells were studied: (1) the effect of hydrophobic environment on the kinetics of thermal transformation in the photolysis of rhodopsin; (2) effects of cholesterol in microvillar membranes on protein-lipid interaction; (3) the effect of membrane proteins on the dynamic properties of li...

Cone photoreceptors of the vertebrate retina terminate their response to light much faster than rod photoreceptors. However, the molecular mechanisms underlying this rapid response termination in cones are poorly understood. The experiments presented here tested two related hypotheses: first, that the rapid decay rate of metarhodopsin (Meta) II in red-sensitive cones depends on interactions bet...