Two mechanisms of permeation of small neutral molecules and hydrated ions across phospholipid bilayers

Volkov, Alexander G.; Paula, Stefan; Deamer, David W.

doi:10.1016/s0302-4598(96)05097-0

Cited by 577 publications

(288 citation statements)

References 17 publications

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“…2b-d). These results suggest that the TRPV2 channel can accommodate partially hydrated Ca 2 þ , Na þ and K þ ions 26 , as well as large organic cations 27 in the apo state. Position of the ARD and pore helix in full-length TRPV2.…”

Section: Resultsmentioning

confidence: 82%

Structure of the Full-Length TRPV2 Channel by Cryo-EM

et al. 2016

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Transient receptor potential (TRP) proteins form a superfamily Ca 2 þ -permeable cation channels regulated by a range of chemical and physical stimuli. Structural analysis of a 'minimal' TRP vanilloid subtype 1 (TRPV1) elucidated a mechanism of channel activation by agonists through changes in its outer pore region. Though homologous to TRPV1, other TRPV channels (TRPV2-6) are insensitive to TRPV1 activators including heat and vanilloids. To further understand the structural basis of TRPV channel function, we determined the structure of full-length TRPV2 at B5 Å resolution by cryo-electron microscopy. Like TRPV1, TRPV2 contains two constrictions, one each in the pore-forming upper and lower gates. The agonist-free full-length TRPV2 has wider upper and lower gates compared with closed and agonist-activated TRPV1. We propose these newly revealed TRPV2 structural features contribute to diversity of TRPV channels.

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Section: Resultsmentioning

confidence: 82%

Structure of the Full-Length TRPV2 Channel by Cryo-EM

et al. 2016

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“…This finding was verified by using myristoleate and palmitoleate vesicles prepared with K ϩ (Table 1). This transport pathway avoids the electrostatic barrier to transport of ions by diffusion through the hydrophobic core (48), and it allows fast cation permeation through fatty acid vesicles, relative to model membranes composed of phospholipids, which have flip-flop lifetimes of several hours (49).…”

Section: Resultsmentioning

confidence: 99%

Membrane growth can generate a transmembrane pH gradient in fatty acid vesicles

Chen

Szostak²

2004

Proc. Natl. Acad. Sci. U.S.A.

145

140

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Electrochemical proton gradients are the basis of energy transduction in modern cells, and may have played important roles in even the earliest cell-like structures. We have investigated the conditions under which pH gradients are maintained across the membranes of fatty acid vesicles, a model of early cell membranes. We show that pH gradients across such membranes decay rapidly in the presence of alkali-metal cations, but can be maintained in the absence of permeable cations. Under such conditions, when fatty acid vesicles grow through the incorporation of additional fatty acid, a transmembrane pH gradient is spontaneously generated. The formation of this pH gradient captures some of the energy released during membrane growth, but also opposes and limits further membrane area increase. The coupling of membrane growth to energy storage could have provided a growth advantage to early cells, once the membrane composition had evolved to allow the maintenance of stable pH gradients.

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“…It seems to be optimal for the passage of many hydrated or partially hydrated anions, such as NO 3 − (3.4 Å), Cl − (3.32 Å), Br − (3.3 Å), and I − (3.31 Å in radius) (Fig. S7A) (29). Interestingly, the cylindrical β-barrel pore in TtMscS is strikingly similar to the mouth of the ion channel pore of the anion-selective eukaryotic glutamate-gated chloride (GluCl) channel in both charge distribution (partially positive charge) and size (∼3.8 Å in radius).…”

Section: Tmmentioning

confidence: 99%

Structure and molecular mechanism of an anion-selective mechanosensitive channel of small conductance

Zhang

Wang

Feng

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Mechanosensitive (MS) channels are universal cellular membrane pores. Bacterial MS channels, as typified by MS channel of small conductance (MscS) from Escherichia coli (EcMscS), release osmolytes under hypoosmotic conditions. MS channels are known to be ion selective to different extents, but the underlying mechanism remains poorly understood. Here we identify an anion-selective MscS channel from Thermoanaerobacter tengcongensis (TtMscS). The structure of TtMscS closely resembles that of EcMscS, but it lacks the large cytoplasmic equatorial portals found in EcMscS. In contrast, the cytoplasmic pore formed by the C-terminal β-barrel of TtMscS is larger than that of EcMscS and has a strikingly different pattern of electrostatic surface potential. Swapping the β-barrel region between TtMscS and EcMscS partially switches the ion selectivity. Our study defines the role of the β-barrel in the ion selection of an anion-selective MscS channel and provides a structural basis for understanding the ion selectivity of MscS channels.crystal structure | anion selection | cytoplasmic region | electrophysiology | single channel recording

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Two mechanisms of permeation of small neutral molecules and hydrated ions across phospholipid bilayers

Cited by 577 publications

References 17 publications

Structure of the Full-Length TRPV2 Channel by Cryo-EM

Structure of the Full-Length TRPV2 Channel by Cryo-EM

Membrane growth can generate a transmembrane pH gradient in fatty acid vesicles

Structure and molecular mechanism of an anion-selective mechanosensitive channel of small conductance

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