A cluster of cytoplasmic histidine residues specifies pH dependence of the AE2 plasma membrane anion exchanger

Article Abstract:

A study on the regulatory mechanism of the nonerythroid anion exchanger AE2 by the intracellular protons, reveals its high sensitivity to intracellular pH. The intracellular pH sensor is determined to be the four histidine residues inside the N-terminal, cytoplasmic domain of the pH-sensitive AE2 and AE3 exchangers. This domain is not found in the erythroid anion exchanger. The determined pH sensitivity AE2 and AE3 are consistent with their physiological activities. A new feedback mechanism is also proposed involving direct control of anion exchangers by intracellular protons.

author: Kopito, Ron R., Sekler, Israel, Kobayashi, Sumire
Plasma membranes, Protons, Histidine, Hydrogen-ion concentration

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Unique aspects of cytoplasmic male sterility and fertility restoration in Brassica napus

Article Abstract:

Cytoplasmic male sterility (CMS) is a common mitochondrially encoded trait leading to the failure of a plant to produce functional pollen. Two types of CMS, nap and pol, are endogenous to the oilseed rape species Brassica napus. Molecular and genetic analyses of the systems are summarized, revealing certain unique aspects of CMS and fertility restoration in Brassica. These may be significant in understanding the evolution of genes involved in the trait and their mechanisms.

author: Brown, G.G.
Brassica, Cytoplasmic inheritance, Sterility in plants, Plant sterility

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Unlocking family secrets: K+ channel transmembrane domains

Article Abstract:

The transmembrane domain of a highly cation-selective ion channel is a 40 A-thick lipid bilayer membrane that contains the K+ channel (KcsA). The KcsA is a tetrameter of two transmembrane-spanning L helices which has been found to be highly-sensitive. It only allows a very specific subset of ions to transit the membrane to prevent cell disfunction and cell death. The sequence of high selectivity of KcsA is characterized by glycine, tyrosine, glycine residues.

author: Clapham, David E.
Potassium channels, Ionic mobility

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subjects list: Research, Physiological aspects, Cell membranes
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