Biomaterial Database

Inhibition of vacuolar ion channels by polyamines. 1999

O R Dobrovinskaya, and J Muñiz, and I I Pottosin

Centro Universitario de Investigaciones Biomedicas, Av. 25 de Julio s/n, Apdo Postal/P.O. Box #199, 28047 Colima, Mexico.

In this work, direct effects of cytosolic polyamines on the two principle vacuolar ion channels were studied by means of patch-clamp technique. Fast and slow activating vacuolar channels were analyzed on membrane patches isolated from vacuoles of the red beet taproot. The potency of the fast and of the slow vacuolar channel blockage by polyamines decreased with a decrease of the polycation charge, spermine4+ > spermidine3+ > putrescine2+. In contrast to the inhibition of the fast vacuolar channel, the blockage of the slow vacuolar channel by polyamines displayed a pronounced voltage-dependence. Hence, in the presence of high concentration of polyamines the slow vacuolar channel was converted into a strong inward rectifier as evidenced by its unitary current-voltage characteristic. The blockage of the slow vacuolar channel by polyamines was relieved at a large depolarization, in line with the permeation of polyamines through this channel. The voltage-dependence of blockage was analyzed in terms of the conventional model, assuming a single binding site for polyamines within the channel pore. Taking advantage of a simple linear structure of naturally occurring polyamines, conclusions on a possible architecture of the slow vacuolar channel pore were drawn. The role of common polyamines in regulation of vacuolar ion transport was discussed.

UI	MeSH Term	Description	Entries
D007473	Ion Channels	Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.	Membrane Channels,Ion Channel,Ionic Channel,Ionic Channels,Membrane Channel,Channel, Ion,Channel, Ionic,Channel, Membrane,Channels, Ion,Channels, Ionic,Channels, Membrane
D011700	Putrescine	A toxic diamine formed by putrefaction from the decarboxylation of arginine and ornithine.	1,4-Butanediamine,1,4-Diaminobutane,Tetramethylenediamine,1,4 Butanediamine,1,4 Diaminobutane
D003594	Cytoplasmic Granules	Condensed areas of cellular material that may be bounded by a membrane.	Cytoplasmic Granule,Granule, Cytoplasmic,Granules, Cytoplasmic
D013095	Spermidine	A polyamine formed from putrescine. It is found in almost all tissues in association with nucleic acids. It is found as a cation at all pH values, and is thought to help stabilize some membranes and nucleic acid structures. It is a precursor of spermine.
D013096	Spermine	A biogenic polyamine formed from spermidine. It is found in a wide variety of organisms and tissues and is an essential growth factor in some bacteria. It is found as a polycation at all pH values. Spermine is associated with nucleic acids, particularly in viruses, and is thought to stabilize the helical structure.
D017136	Ion Transport	The movement of ions across energy-transducing cell membranes. Transport can be active, passive or facilitated. Ions may travel by themselves (uniport), or as a group of two or more ions in the same (symport) or opposite (antiport) directions.	Antiport,Ion Cotransport,Ion Exchange, Intracellular,Symport,Uniport,Active Ion Transport,Facilitated Ion Transport,Passive Ion Transport,Cotransport, Ion,Exchange, Intracellular Ion,Intracellular Ion Exchange,Ion Transport, Active,Ion Transport, Facilitated,Ion Transport, Passive,Transport, Active Ion,Transport, Ion
D018408	Patch-Clamp Techniques	An electrophysiologic technique for studying cells, cell membranes, and occasionally isolated organelles. All patch-clamp methods rely on a very high-resistance seal between a micropipette and a membrane; the seal is usually attained by gentle suction. The four most common variants include on-cell patch, inside-out patch, outside-out patch, and whole-cell clamp. Patch-clamp methods are commonly used to voltage clamp, that is control the voltage across the membrane and measure current flow, but current-clamp methods, in which the current is controlled and the voltage is measured, are also used.	Patch Clamp Technique,Patch-Clamp Technic,Patch-Clamp Technique,Voltage-Clamp Technic,Voltage-Clamp Technique,Voltage-Clamp Techniques,Whole-Cell Recording,Patch-Clamp Technics,Voltage-Clamp Technics,Clamp Technique, Patch,Clamp Techniques, Patch,Patch Clamp Technic,Patch Clamp Technics,Patch Clamp Techniques,Recording, Whole-Cell,Recordings, Whole-Cell,Technic, Patch-Clamp,Technic, Voltage-Clamp,Technics, Patch-Clamp,Technics, Voltage-Clamp,Technique, Patch Clamp,Technique, Patch-Clamp,Technique, Voltage-Clamp,Techniques, Patch Clamp,Techniques, Patch-Clamp,Techniques, Voltage-Clamp,Voltage Clamp Technic,Voltage Clamp Technics,Voltage Clamp Technique,Voltage Clamp Techniques,Whole Cell Recording,Whole-Cell Recordings
D019663	Chenopodiaceae	The goosefoot plant family of the order Caryophyllales, subclass Caryophyllidae, class Magnoliopsida. It includes beets and chard (BETA VULGARIS), as well as SPINACH, and salt tolerant plants.	Halogeton,Kochia,Salicornia,Suaeda,Halogetons,Kochias,Salicornias,Suaedas