Histidine-rich calcium-binding protein: a molecular integrator of cardiac excitation-contraction coupling.

During mammalian cardiomyocyte excitation-contraction coupling, Ca2+ influx through voltage-gated Ca2+ channels triggers Ca2+ release from the sarcoplasmic reticulum (SR) through ryanodine receptor channels. This Ca2+-induced Ca2+ release mechanism controls cardiomyocyte contraction and is exquisitely regulated by SR Ca2+ levels. The histidine-rich calcium-binding protein (HRC) and its aspartic acid-rich paralogue aspolin are high-capacity, low-affinity Ca2+-binding proteins.

Non-inositol 1,4,5-trisphosphate (IP) receptor IP-binding proteins.

Conventionally, myo-D-inositol 1, 4,5-trisphosphate (IP) is thought to exert its second messenger effects through the gating of IPR Ca release channels, located in Ca-storage organelles like the endoplasmic reticulum. However, there is considerable indirect evidence to support the concept that IP might interact with other, non-IPR proteins within cells. To explore this possibility further, the Protein Data Bank was searched using the term "IP3".

-D-inositol Trisphosphate Signalling in Oomycetes.

Oomycetes are pathogens of plants and animals, which cause billions of dollars of global losses to the agriculture, aquaculture and forestry sectors each year. These organisms superficially resemble fungi, with an archetype being , the cause of late blight of tomatoes and potatoes. Comparison of the physiology of oomycetes with that of other organisms, such as plants and animals, may provide new routes to selectively combat these pathogens.

Evolution of the cardiac dyad.

Cardiac dyads are the site of communication between the sarcoplasmic reticulum (SR) and infoldings of the sarcolemma called transverse-tubules (TT). During heart excitation-contraction coupling, Ca-influx through L-type Ca channels in the TT is amplified by release of Ca-from the SR via type 2 ryanodine receptors, activating the contractile apparatus. Key proteins involved in cardiac dyad function are bridging integrator 1 (BIN1), junctophilin 2 and caveolin 3.

Ryanodine receptor calcium release channels in trophoblasts and their role in cell migration.

Trophoblasts are specialized epithelial cells of the placenta that are involved in invasion, communication and the exchange of materials between the mother and fetus. Cytoplasmic Ca ([Ca]) plays critical roles in regulating such processes in other cell types, but relatively little is known about the mechanisms that control this second messenger in trophoblasts. In the current study, the presence of RyRs and their accessory proteins in placental tissues and in the BeWo choriocarcinoma, a model trophoblast cell-line, were examined using immunohistochemistry and Western immunoblotting.

Evolution of Excitation-Contraction Coupling.

In mammalian cardiomyocytes, Ca influx through L-type voltage-gated Ca channels (VGCCs) is amplified by release of Ca via type 2 ryanodine receptors (RyR2) in the sarcoplasmic reticulum (SR): a process termed Ca-induced Ca-release (CICR). In mammalian skeletal muscles, VGCCs play a distinct role as voltage-sensors, physically interacting with RyR1 channels to initiate Ca release in a mechanism termed depolarisation-induced Ca-release (DICR). In the current study, we surveyed the genomes of animals and their close relatives, to explore the evolutionary history of genes encoding three proteins pivotal for ECC: L-type VGCCs; RyRs; and a protein family that anchors intracellular organelles to plasma membranes, namely junctophilins (JPHs).