We recently cloned a homologue of the bovine parathyroid calcium receptor from the kidney of a spiny dogfish (Squalus acanthias) and termed this new protein SKCaR. SKCaR senses alterations in extracellular Mg2+ after its expression in human embryonic kidney cells (Nearing J, Betka M, Quinn S, Hentschel H, Elger M, Baum M, Bai M, Chattopadyhay N, Brown E, Hebert S, and Harris HW. Proc Natl Acad....

ABSTRACT. The transient receptor potential (TRP) superfamily of proteins is cation-selective ion channels with six predicted transmembrane segments and intracellularly localized amino and carboxyl termini. Members of the TRP superfamily are identified on the basis of amino acid sequence and structural similarity and are classified into TRPC, TRPV, TRPM, TRPP, TRPN, and TRPML subfamilies. TRP ch...

The kidney plays an important role in maintaining the systemic Ca2+ and Mg2+ balance. Thus the renal reabsorptive capacity of these cations can be amended to adapt to disturbances in plasma Ca2+ and Mg2+ concentrations. The reabsorption of Ca2+ and Mg2+ is driven by transport of other electrolytes, sometimes through selective channels and often supported by hormonal stimuli. It is, therefore, n...

Proper regulation of the intracellular ion concentration is essential to maintain life and is achieved by ion transporters that transport their substrates across the membrane in a strictly regulated manner. MgtE is a Mg(2+) transporter that may function in the homeostasis of the intracellular Mg(2+) concentration. A recent crystallographic study revealed that its cytosolic domain undergoes a Mg...

The distal convoluted tubule plays a significant role in renal magnesium conservation. Although the cells of the distal convoluted tubule possess the vitamin D receptor, little is known about the effects of 1alpha,25-dihydroxyvitamin D [1,25(OH)(2)D(3)] on magnesium transport. In this study, we examined the effect of 1,25(OH)(2)D(3) on distal cellular magnesium uptake and the modulation of this...

Internal bacterial concentration of Mg2+, the most abundant divalent cation in living cells, is estimated to be in the single millimolar range. However, many bacteria will thrive in media with only micromolars of Mg2+, by using a range of intensely studied and highly efficient import mechanisms, as well as in media with very high magnesium concentration, presumably mediated by currently unknown...

Two-component signal transduction systems (2-CS) play an important role in bacterial pathogenesis. In the work presented here, we have studied the effects of a mutation in the Mycobacterium tuberculosis (Mtb) PhoPR 2-CS on the pathogenicity, physiology and global gene expression of this bacterial pathogen. Disruption of PhoPR causes a marked attenuation of growth in macrophages and mice and pre...

Cardiac troponin C (cTnC) is a key effector in cardiac muscle excitation-contraction coupling as the Ca2+ sensing subunit responsible for controlling contraction. In this study, we generated several FRET sensors for divalent cations based on cTnC flanked by a donor fluorescent protein (CFP) and an acceptor fluorescent protein (YFP). The sensors report Ca2+ and Mg2+ binding, and relay global str...