Molecular basis of plant-specific acid activation of K+ uptake channels

The uptake of potassium ions (K+) accompanied by an acidification of the apoplasm is a prerequisite for stomatal opening. The acidification (approximately 2–2.5 pH units) is perceived by voltage-gated inward potassium channels (Kin) that then can open their pores with lower energy cost. The sensory units for extracellular pH in stomatal Kin channels are proposed to be histidines exposed to the apoplasm. However, in the Arabidopsis thaliana stomatal Kin channel KAT1, mutations in the unique histidine exposed to the solvent (His267) do not affect the pH dependency. We demonstrate in the present study that His267 of the KAT1 channel cannot sense pH changes since the neighbouring residue Phe266 shifts its pKa to undetectable values through a cation–π interaction. Instead, we show that Glu240 placed in the extracellular loop between transmembrane segments S5 and S6 is involved in the extracellular acid activation mechanism. Based on structural models we propose that this region may serve as a molecular link between the pH- and the voltage-sensor. Like Glu240, several other titratable residues could contribute to the pH-sensor of KAT1, interact with each other and even connect such residues far away from the voltage-sensor with the gating machinery of the channel.

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Renilla Bioluminescence: A Morphologic Approach to the Location of Photocytes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100051050 ◽

1974 ◽

Vol 32 ◽

pp. 208-209

Author(s):

Ben O. Spurlock ◽

Milton J. Cormier

Keyword(s):

Excited State ◽

Ground State ◽

Molecular Basis ◽

Light Emission ◽

Chemical Basis ◽

Electronic Excited State ◽

Colonial Form ◽

The Common ◽

Eighteenth And Nineteenth Centuries ◽

Catalyzed Oxidation

The phenomenon of bioluminescence has fascinated layman and scientist alike for many centuries. During the eighteenth and nineteenth centuries a number of observations were reported on the physiology of bioluminescence in Renilla, the common sea pansy. More recently biochemists have directed their attention to the molecular basis of luminosity in this colonial form. These studies have centered primarily on defining the chemical basis for bioluminescence and its control. It is now established that bioluminescence in Renilla arises due to the luciferase-catalyzed oxidation of luciferin. This results in the creation of a product (oxyluciferin) in an electronic excited state. The transition of oxyluciferin from its excited state to the ground state leads to light emission.

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Androgen-induced plasticity at a “vocal” neuromuscular synapse

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100167895 ◽

1994 ◽

Vol 52 ◽

pp. 32-33

Author(s):

Darcy B. Kelley ◽

Martha L. Tobias ◽

Mark Ellisman

Keyword(s):

Xenopus Laevis ◽

Motor Neurons ◽

Sexual Differentiation ◽

Molecular Basis ◽

Neuromuscular Synapse ◽

Sexually Dimorphic ◽

Intracellular Protein ◽

Developmental Program ◽

Androgen Action ◽

Clawed Frog

Brain and muscle are sexually differentiated tissues in which masculinization is controlled by the secretion of androgens from the testes. Sensitivity to androgen is conferred by the expression of an intracellular protein, the androgen receptor. A central problem of sexual differentiation is thus to understand the cellular and molecular basis of androgen action. We do not understand how hormone occupancy of a receptor translates into an alteration in the developmental program of the target cell. Our studies on sexual differentiation of brain and muscle in Xenopus laevis are designed to explore the molecular basis of androgen induced sexual differentiation by examining how this hormone controls the masculinization of brain and muscle targets.Our approach to this problem has focused on a highly androgen sensitive, sexually dimorphic neuromuscular system: laryngeal muscles and motor neurons of the clawed frog, Xenopus laevis. We have been studying sex differences at a synapse, the laryngeal neuromuscular junction, which mediates sexually dimorphic vocal behavior in Xenopus laevis frogs.

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A molecular basis for opiate action

Essays in Biochemistry ◽

10.1042/bse0330065 ◽

1998 ◽

Vol 33 ◽

pp. 65-77 ◽

Cited By ~ 17

Author(s):

Dominique Massotte ◽

Brigitte L. Kieffer

Keyword(s):

Molecular Basis

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Treatment of severe endometriosis with an aromatase inhibitor: A novel indication and its molecular basis

Journal of the Society for Gynecologic Investigation ◽

10.1016/s1071-5576(97)86305-8 ◽

1998 ◽

Vol 5 (1) ◽

pp. 96A-96A ◽

Cited By ~ 2

Author(s):

K ZEITOUN ◽

K TAKAYAMA ◽

R GUNBY ◽

B CARR ◽

S BULUN

Keyword(s):

Aromatase Inhibitor ◽

Molecular Basis

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Molecular Basis of Neuropsychiatric Disorders: from Bench to Bedside

10.1016/s1877-1173(19)x0008-3 ◽

2019 ◽

Keyword(s):

Molecular Basis ◽

Neuropsychiatric Disorders

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Emerging Nutrition Gaps in a World of Affluence - Micronutrient Intake and Status Globally

International Journal for Vitamin and Nutrition Research ◽

10.1024/0300-9831/a000068 ◽

2011 ◽

Vol 81 (4) ◽

pp. 238-239 ◽

Cited By ~ 3

Author(s):

Manfred Eggersdorfer ◽

Paul Walter

Keyword(s):

Developing Countries ◽

Human Health ◽

Old Age ◽

Molecular Basis ◽

Health Benefit ◽

Developed Countries ◽

Micronutrient Deficiencies ◽

New Science ◽

Health And Nutrition ◽

Micronutrient Intake

Nutrition is important for human health in all stages of life - from conception to old age. Today we know much more about the molecular basis of nutrition. Most importantly, we have learnt that micronutrients, among other factors, interact with genes, and new science is increasingly providing more tools to clarify this interrelation between health and nutrition. Sufficient intake of vitamins is essential to achieve maximum health benefit. It is well established that in developing countries, millions of people still suffer from micronutrient deficiencies. However, it is far less recognized that we face micronutrient insufficiencies also in developed countries.

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