Microscopic approaches to ion transport through transmembrane channels: the model system gramicidin

1987 ◽  
Vol 91 (27) ◽  
pp. 6582-6591 ◽  
Author(s):  
Peter C. Jordan
Keyword(s):  
Ion Transport ◽  
Model System ◽  
Transmembrane Channels

An Ion Transport Switch Based on Light-Responsive Conformation-Dependent G-Quadruplex Transmembrane Channels

2021 ◽  
Author(s):  
Chunying Li ◽  
Hui Chen ◽  
Xiaohai Yang ◽  
Kemin Wang ◽  
Jianbo Liu
Keyword(s):  
Ion Transport ◽  
Selective Transport ◽  
G Quadruplex ◽  
Transmembrane Channels

A light-responsive ion transport switch has been developed based on conformation-dependent azobenzene-incorporated lipophilic G-quadruplex channels, which provides a new smart approach for the selective transport of K+ ions across the...

Artificial Transmembrane Channels for Sodium and Potassium

2002 ◽  
Vol 85 (3) ◽  
pp. 219-241 ◽  
Author(s):  
Peter J. Cragg
Keyword(s):  
Ion Transport ◽  
Alkali Metals ◽  
Structural Features ◽  
Artificial System ◽  
Ion Specificity ◽  
Ion Concentrations ◽  
Transmembrane Channels ◽  
Essential Function ◽  
Membrane Spanning ◽  
Sodium And Potassium

Transport of alkali metals, particularly sodium and potassium, across cell membranes is an essential function performed by special proteins that enable cells to regulate inter- and extracellular ion concentrations with exceptional selectivity. The importance of these channel-forming proteins has led to researchers emulating of their structural features: an ion-specific filter and conduction at rates up to 108 ions per second. Synthetic helical and cyclic polypeptides form channels, however, the specificity of ion transport is often low. Ion-specific macrocycles have been used as filters from which membrane-spanning derivatives have been prepared. Success has been limited as many compounds act as ion carriers rather than forming transmembrane channels. Surfactant compounds also allow ions to cross membranes but any specificity is serendipitous. Overall it seems possible to mimic either ion specificity or efficient transmembrane ion transport. The goal for the future will be to combine both characteristics in one artificial system.

A Protozoan Model for Golgi-Associated Calcification

1971 ◽  
Vol 29 ◽  
pp. 332-333
Author(s):  
D. C. Williams ◽  
D. E. Outka
Keyword(s):  
Golgi Apparatus ◽  
Organic Matrix ◽  
Model System ◽  
Sequential Formation

Many studies have shown that the Golgi apparatus is involved in a variety of synthetic activities, and probably no Golgi product is more elaborate than the scales produced by various kinds of phytoflagellates. The formation of calcified scales (coccoliths, Fig. 1,2) of the coccolithophorid phytoflagellates provides a particularly interesting model system for the study of biological mineralization, and the sequential formation of Golgi products.The coccoliths of Hymenomonas carterae consist of a scale-like base (Fig. 2 and 4, b) with a highly structured calcified (CaCO3) rim composed of two distinct elements which alternate about the base periphery (Fig. 1 and 3, A, B). Each element is enveloped by a sheath-like organic matrix (Fig. 3; Fig. 4, m).

Existence of DNA in yeast microbodies

1978 ◽  
Vol 36 (2) ◽  
pp. 232-233
Author(s):  
Masako Osumi ◽  
Misuzu Nagano ◽  
Hiroko Kazama
Keyword(s):  
Catalase Activity ◽  
Buoyant Density ◽  
Model System ◽  
Contour Length ◽  
Native State ◽  
Normal Alkane ◽  
Remarkable Increase ◽  
Dna Molecule ◽  
Mitochondrial Dnas

We have found that microbodies appeared profusely together with a remarkable increase in catalase activity in normal alkane-grown cells of hydrocarbon-utilizing Candida yeasts, and that the microbodies multiplied by division in these cells. These features of Candida yeasts seem to provide a useful model system for studies on the biogenesis of the microbody. Subsequently, we have succeeded in isolation of Candida microbodies in an apparently native state, as judged biochemically and morphologically. The presence of DNA in the purified microbody fraction thus obtained was proved by the diphenylamine method. DNA molecule of about 15 urn in contour length was released from an isolated microbody. The physicochemical analyses of the microbody DNA revealed that its buoyant density differed from nuclear and mitochondrial DNAs. All these results lead us to the possibility that there is a novel type of DNA in microbodies.

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