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Cover Image
Cover Image
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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Research News
A symporter’s secrets shown
New JGP study explores the thermodynamic cycle and cation preference of the sugar symporter MelB.
Commentary
Subtle mutation, far-reaching effects
Insufficient sodium-ion extrusion by mutated Na+,K+-ATPases causes hyperaldosteronism.
Milestone in Physiology
The envenomation of general physiology throughout the last century
Sack discusses the evolution of toxin research in JGP over the last 100 years.
Review
Threading the biophysics of mammalian Slo1 channels onto structures of an invertebrate Slo1 channel
Zhou et al. consider the biophysics of large-conductance Ca2+-activated Slo1 channels in the context of Aplysia Slo1 structures.
Article
On the effect of hyperaldosteronism-inducing mutations in Na/K pumps
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.
