Cover picture: X-ray crystal structure of the Salmonella typhimurium melibiose transporter MelBSt (PDB ID 4M64). Residues important for binding of melibiose and coupling cations (Na+, Li+, or H+) are shown by sticks. Cooperative binding of the cosubstrates and competitive binding of the cations were experimentally determined by thermodynamic studies (see Research article by Hariharan and Guan, 1029–1039).
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Milestone in Physiology
JGP 100th Anniversary
Zhou et al. consider the biophysics of large-conductance Ca2+-activated Slo1 channels in the context of Aplysia Slo1 structures.
Mutated Na/K pumps in adrenal adenomas are thought to cause hyperaldosteronism via a gain-of-function effect involving a depolarizing inward current. The findings of Meyer et al. suggest instead that the common mechanism by which Na/K pump mutants lead to hyperaldosteronism is a loss-of-function.
Thermodynamic cooperativity of cosubstrate binding and cation selectivity of Salmonella typhimurium MelB
The melibiose symporter MelB couples melibiose transport to that of cations such as Na+. Hariharan and Guan show that the binding of Na+ and melibiose is thermodynamically cooperative and that Na+ coupling is based on ion concentrations and competitive binding, but not ion selectivity.
The voltage sensor of excitation–contraction coupling in mammals: Inactivation and interaction with Ca2+
In excitation–contraction coupling, voltage-sensing modules (VSMs) of CaV1.1 Ca2+ channels simultaneously gate the associated pore and Ca2+ release channels in the sarcoplasmic reticulum. Ferreira Gregorio et al. find that VSMs adopt two inactivated states, and the degree of inactivation is dependent on external Ca2+ and the mouse strain used.