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Y Fukada

Publications and source records attributed to Y Fukada.

At least 163 records · Page 9Linked to original sources
PubMed1982

Activation of phosphodiesterase in frog rod outer segment by rhodopsin analogues.

Activation of guanosine 3',5'-cyclic monophosphate (cGMP) phosphodiesterase (EC 3.1.4.35) in frog rod outer segment membrane by rhodopsin analogues has been investigated. A rhodopsin analogue modified at the Schiff-base linkage (N-retinyl-opsin) or the beta-ionone ring (3-dehydro-rhodopsin) in the retinylidene chromophore of rhodopsin has some ability in activation of the enzyme. In consideration of our previous observation that opsin including a retinal-oxime can activate the enzyme, it seems likely that the Schiff-base linkage is not always necessary for the phosphodiesterase activation. On the other hand, a change in the length of the side chain of retinal (complex of opsin and beta-ionone, beta-ionylideneacetaldehyde or retinylideneacetaldehyde) or dissection of the conjugate double-bond system of the side chain (retro-gamma-rhodopsin) remarkably reduces the activation ability. However, 5,8-epoxy-rhodopsin having a similar dissected conjugate double-bond system induces some enzyme activation because of its rigid conformation around C7-C8-C9 single bonds. Consequently, it is suggested that the necessary portion of rhodopsin chromophore for the activation of the enzyme is the rigid conjugate double-bond system between the beta-ionone ring and the Schiff-base linkage in its all-trans form.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1981

Activation of phosphodiesterase in frog rod outer segment by an intermediate of rhodopsin photolysis I.

Guanosine 3',5'-cyclic monophosphate phosphodiesterase (EC 3.1.4.1) in frog rod outer segment prepared by a sucrose stepwise density gradient method was activated by light in the presence of GTP. Rhodopsin in rod outer segment was solubilized with sucrose laurylmonoester and then purified by concanavalin A-Sepharose column. Addition of photo-bleached preparation of the purified rhodopsin to the crude rod outer segment, which had been prepared by 43% (w/w) sucrose floatation, caused the activation of phosphodiesterase in the dark, while each component of the photo-product eluted from the column (all-trans retinal and opsin) did not. Regenerated rhodopsin prepared from 11-cis retinal and purified opsin activated phosphodiesterase when it was bleached. From these facts it is suggested that an intermediate or a process of photolysis of rhodopsin causes activation of phosphodiesterase.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1981

Activation of phosphodiesterase in frog rod outer segment by an intermediate of rhodopsin photolysis. II.

Frog (Rana catesbeiana) rod outer segment membrane contains cyclic GMP phosphodiesterase (EC 3.1.4.1). Irradiation of dark-adapted rod outer segment membrane increased the enzyme activity by 5-20-fold in the presence of GTP. The phosphodiesterase in rod outer segment membrane is also activated by mixing a photo-product of 11-cis (regenerated), 9-cis or 7-cis rhodopsin which is stable at 0 degrees C. However, neither opsin in the membrane nor all-trans retinal activates the enzyme. The phosphodiesterase in rod outer segment membrane is also activated by irradiation at -4 degrees C. Thus, we conclude that the phosphodiesterase in activated by a common photolysis intermediate of these rhodopsin isomers, perhaps before metarhodopsin II decays.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1976

Identification, classification and anatomical segregation of cells with X-like and Y-like properties in the lateral geniculate nucleus of old-world primates.

1. All the cells (158) that we studied in the lateral geniculate nuclei of Macaca nemestrina and Macaca irus could be distinguished as either X-like or Y-like on the basis of their responses to tests developed to classify cat retinal and lateral geniculate nucleus cells. These tests include responses to stationary spots, fast moving wands and moving gratings. 2. Response latencies to electrical stimulation of the optic chiasm were determined for 130 cells; no X-like cell showed a latency shorter than 1-7 ms, no Y-like cell showed a latency longer than 1-6 ms. Primate lateral geniculate nucleus cells with X-like properties thus receive their excitatory input from retinal cells with slowly conducting axons and these most probably include the tonic ganglion cells described by Gouras (1968, 1969); Y-like lateral geniculate nucleus cells are driven by retinal cells with faster conducting axons, most probably including the phasic ganglion cells described by Gouras. 3. Wiesel & Hubel (1966) classified monkey lateral geniculate nucleus cells into four main types based on their receptive-field properties, as revealed by spectrally and spatially distinct stimuli. We find that all Type I and Type II cells show X-like properties; all type IV cells show Y-like properties. Type III consists of a subtype that show X-like properties, here termed Type IIIx, and a subtype that show Y-like properties, here termed Type IIIy. 4. The first cells encountered as the micro-electrode reached the lateral geniculate nucleus were always X-like. In some penetrations only X-like cells were encountered as the electrode moved downward through the lateral geniculate nucleus. In the remaining penetrations, after recording X-like cells through most of the lateral geniculate nucleus, Y-like cells were then encountered. No X-like cells were found below Y-like cells. thus these two classes of cells are anatomically segregated within the primate lateral geniculate nucleus. Electrode marking showed the borger between X-like and Y-like cells to correspond to the border between the paro- and magnocellular layers of the lateral geniculate nucleus. Thus X-like cells (i.e. Types I, II and IIIx) occur in the parvocellular layers, Y-like cells (i.e. Types IIIy and IV)in the magnocellular layers.

Animals↗