Seibutsu Butsuri
Online ISSN : 1347-4219
Print ISSN : 0582-4052
ISSN-L : 0582-4052
Volume 51 , Issue 2
Issue 294
Showing 1-19 articles out of 19 articles from the selected issue
Perspective
Overview
  • Yuichi FUJITA, Genji KURISU
    2011 Volume 51 Issue 2 Pages 066-071
    Published: 2011
    Released: March 30, 2011
    JOURNALS FREE ACCESS
    Protochlorophyllide (Pchlide) reduction is the final step to make up the spectroscopic properties of chlorophyll a in biosynthesis of chlorophyll. During evolution, photosynthetic organisms have invented two structurally unrelated Pchlide reductases; light-dependent Pchlide reductase (LPOR) and light-independent (dark-operative) Pchlide reductase (DPOR). LPOR is an NADPH-dependent enzyme operating as a key enzyme for the light-dependent greening in angiosperms, and DPOR is a nitrogenase-like enzyme that allows gymnosperms, algae, cyanobacteria and photosynthetic bacteria to produce (bacterio)chlorophylls even in the dark. We will review recent major research progresses on Pchlide reductases, especially, crystallographic structure and proposed reaction mechanism of DPOR. Differential operation and evolutionary implications of these enzymes are also discussed.
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Review
  • Tatsuki KUROKAWA, Yasushi OKAMURA
    2011 Volume 51 Issue 2 Pages 072-075
    Published: 2011
    Released: March 30, 2011
    JOURNALS FREE ACCESS
    The voltage-sensor domain (VSD) is the key module for voltage sensing of transmembrane proteins. Recently, voltage-sensor only protein (VSOP) that contains a single VSD but no pore domain was discovered and functions as the voltage-gated proton channel. The fourth transmembrane segment (S4) of VSOP contains three arginines (R1, R2, R3). We found that VSOP truncated just downstream of R2 retains most channel properties. Two assays, PEGylation-protection assay and membrane insertion assay, showed that S4 inserts into the membrane, even if it is truncated between R2 and R3. These findings provide important clues to the molecular mechanism of voltage-gated proton channel.
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  • Suguru KAWATO
    2011 Volume 51 Issue 2 Pages 076-079
    Published: 2011
    Released: March 30, 2011
    JOURNALS FREE ACCESS
    Functions of the hippocampus is dependent on brain-derived-neurosteroids. Because estrogen is synthesized locally in the hippocampus, as well as supplied from the ovary, its functions are attracting much attention. Hippocampal sex-steroids modulate memory-related synaptic plasticity not only slowly but also rapidly. Slow actions of estradiol (E2) occur via nuclear receptors (ERα), while rapid E2 actions occur via synapse-localized ERα. Elevation or decrease of the E2 concentration changes rapidly the density and morphology of spines. Kinase networks are involved downstream of ERα. The long-term depression is modulated rapidly by changes of E2 level. The E2 level is much higher than that in blood circulation. Hippocampus-derived sex-steroids play a major role in modulation of synaptic plasticity.
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Topics
Theoretical and experimental techniques
Salon
Photo Salon
Activity of Regional Branch
Young Voice
Letters from Abroad
Promenade along Protein 3D Structures
Technical term
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