Ca(2+) in neurons is vital to processes such as neurotransmission, neurotoxicity, synaptic development, and gene expression. Disruption of Ca(2+) homeostasis occurs in brain aging and in neurodegenerative disorders. Membrane transporters, among them the calmodulin (CaM)-activated plasma membrane Ca(2+) ATPases (PMCAs) that extrude Ca(2+) from the cell, play a key role in neuronal Ca(2+) homeost...

Mitochondria not only provide cells with energy, but are central to Ca(2+) signaling. Powered by the mitochondrial membrane potential, Ca(2+) enters the mitochondria and is released into the cytosol through a mitochondrial Na(+)/Ca(2+) exchanger. We established that NCLX, a newly discovered mitochondrial Na(+)/Ca(2+) exchanger, is expressed in astrocytes isolated from mice of either sex. Immuno...

Introduction In the heart, excitation-contraction coupling (ECC) is a sequence of events that begins with membrane depolarization by an action potential (AP), followed by activation of voltage-gated Ca channels in the surface membrane, initiation of Ca release from the SR Ca store by CICR, and the resulting contraction. Most of our knowledge of the mechanistic details of ECC originates from stu...

Introduction In the heart, excitation-contraction coupling (ECC) is a sequence of events that begins with membrane depolarization by an action potential (AP), followed by activation of voltage-gated Ca channels in the surface membrane, initiation of Ca release from the SR Ca store by CICR, and the resulting contraction. Most of our knowledge of the mechanistic details of ECC originates from stu...

Introduction In the heart, excitation-contraction coupling (ECC) is a sequence of events that begins with membrane depolarization by an action potential (AP), followed by activation of voltage-gated Ca channels in the surface membrane, initiation of Ca release from the SR Ca store by CICR, and the resulting contraction. Most of our knowledge of the mechanistic details of ECC originates from stu...

Plasma membrane wounds are repaired by a mechanism involving Ca(2+)-regulated exocytosis. Elevation in intracellular [Ca(2+)] triggers fusion of lysosomes with the plasma membrane, a process regulated by the lysosomal synaptotagmin isoform Syt VII. Here, we show that Ca(2+)-regulated exocytosis of lysosomes is required for the repair of plasma membrane disruptions. Lysosomal exocytosis and memb...

In the mammalian central nervous system, the postsynaptic small-conductance Ca(2+)-dependent K(+) (SK) channel has been shown to reduce postsynaptic depolarization and limit Ca(2+) influx through N-methyl-d-aspartate receptors. To examine further the role of the postsynaptic SK channel in synaptic transmission, we studied its action at the Drosophila larval neuromuscular junction (NMJ). Repetit...

Regulation of ion transport in plants is essential for cell function. Abiotic stress unbalances cell ion homeostasis, and plants tend to readjust it, regulating membrane transporters and channels. The plant hormone abscisic acid (ABA) and the second messenger Ca(2+) are central in such processes, as they are involved in the regulation of protein kinases and phosphatases that control ion transpo...

Ca 2 is a major determinant of many biochemical processes in various cell types, from the beginning of new life and egg fertilization to the end of life and cell death.1 In vascular smooth muscle (VSM), physiological resting levels of intracellular free Ca concentration ([Ca ]i) in the nanomolar range are necessary to maintain basal vascular tone.2–4 VSM activation is associated with an increas...

We have previously shown that store-associated microdomains of high Ca(2+) are not essential for exocytosis in RBL-2H3 mucosal mast cells. We have now examined whether Ca(2+) microdomains near the plasma membrane are required, by comparing the secretory responses seen when Ca(2+) influx was elicited by two very different mechanisms. In the first, antigen was used to activate the Ca(2+) release-...