G-Quadruplex-Filtered Selective Ion-to-Ion Current Amplification for Non-Invasive Ion Monitoring in Real Time.

Living cells efflux intracellular ions for maintaining cellular life, so intravital measurements of specific ion signals are of significant importance for studying cellular functions and pharmacokinetics. In this work, de novo synthesis of artificial K -selective membrane and its integration with polyelectrolyte hydrogel-based open-junction ionic diode (OJID) is demonstrated, achieving a real-time K -selective ion-to-ion current amplification in complex bioenvironments. By mimicking biological K channels and nerve impulse transmitters, in-line K -binding G-quartets are introduced across freestanding lipid bilayers by G-specific hexylation of monolithic G-quadruplex, and the pre-filtered K flow is directly converted to amplified ionic currents by the OJID with a fast response time at 100 ms intervals.

Altering CLC stoichiometry by reducing non-polar side-chains at the dimerization interface.

CLC-ec1 is a Cl/H antiporter that forms stable homodimers in lipid bilayers, with a free energy of -10.9 kcal/mol in 2:1 POPE/POPG lipid bilayers. The dimerization interface is formed by four transmembrane helices: H, I, P and Q, that are lined by non-polar side-chains that come in close contact, yet it is unclear as to whether their interactions drive dimerization.

Cryo-EM structure of human Cx31.3/GJC3 connexin hemichannel.

Connexin family proteins assemble into hexameric channels called hemichannels/connexons, which function as transmembrane channels or dock together to form gap junction intercellular channels (GJIChs). We determined the cryo-electron microscopy structures of human connexin 31.3 (Cx31.

Mutation of external glutamate residue reveals a new intermediate transport state and anion binding site in a CLC Cl/H antiporter.

The CLC family of proteins are involved in a variety of physiological processes to control cellular chloride concentration. Two distinct classes of CLC proteins, Cl channels and Cl/H antiporters, have been functionally and structurally investigated over the last several decades. Previous studies have suggested that the conformational heterogeneity of the critical glutamate residue, Glu, could explain the transport cycle of CLC-type Cl/H antiporters.