- Structural determinants of CaV1.1 gating
CaV1.1 is a slowly activating voltage-gated Ca2+ channel that exists in two splice variants with different voltage sensitivities. By making chimeras of these variants, Tuluc et al. show that activation kinetics and voltage dependence are controlled by distinct molecular mechanisms in the voltage-sensing domains of repeats I and IV, respectively.
- P2X7-like currents mediated by TRPM7
Extracellular ATP activates receptors such as P2X ligand-gated ion channels, but it also chelates divalent cations. Nörenberg et al. find that experimental conditions designed to measure P2X7 activity also activate TRPM7 channels, by relieving inhibition by extracellular divalent cations, in HEK293 and rat C6 glioma cells.
- Structure–function relationship of calcins
Calcins are a new and expanding family of ryanodine receptor agonists found in scorpion venom. Xiao and colleagues characterize the structure–function relationships of all known calcins and show both similarities and differences in their form and function.
- Subspecialization of human ocular muscles
Facial muscles are skeletal muscles that control facial expression. Sekulic-Jablanovic et al. characterize orbicularis oculi and extraocular muscles and find divergence in the expression of key molecules for muscle function between facial, extraocular, and quadriceps muscles.
- Ae4 is a Cl−/K+(Na+)-HCO3− exchanger
AE4 is an anion exchanger known to counter transport Cl− and HCO3− across secretory cell membranes. Peña-Münzenmayer et al. show that AE4 is an electroneutral exchanger and that it also transports monovalent cations in the same direction as HCO3−.
- Asymmetrical construction of CFTR’s pore
CFTR is a chloride channel and a member of the ABC transporter superfamily; however, its structure is unknown. By making a series of cysteine mutants, Gao and Hwang show that CFTR lacks the twofold pseudo-symmetry seen in the permeation pathway of bone fide ABC transporters.