1273 C2+ release through ryanodine receptor (RyR) intracellular Ca release channels plays the leading role in the regulation of myocyte contraction. However, Ca signals arising from their less abundant inositol 1,4,5-trisphosphate (InsP 3 )–sensitive counterparts (InsP 3 Rs), also localized to intracellular stores, are emerging as an important modulator of Ca-sensitive processes in cardiac myoc...

A rise in intracellular calcium ([Ca 2 ϩ ] i) in response to binding of inositol 1,4,5 trisphosphate (InsP 3) to its receptors is a ubiquitous signaling system, which is implicated in the control of a myriad of cellular functions (Berridge, 1993). Three distinct InsP 3 receptors are expressed to varying degrees in individual cell types (Wojcikiewicz, 1995). Activation of these receptors results...

Abstract Background The analysis of myo‐inositol phosphates (InsP x ) released by phytases during phytic acid degradation is challenging and time‐consuming, particularly in terms sample preparation, isomer separation, detection. However, a fast robust method crucial when screening for protein engineering approaches, which result large number samples, to ensure reliable identification promising ...

An internal target volume (ITV) accounting for respiratory-induced tumor motion is best obtained using 4DCT. However, when 4DCT is not available, inspiratory/expiratory breath-hold (BH insp, BH exp) CT images have been suggested as an alternative. In such cases, an external fiducial on the abdomen can be used as a substitute for tumor motion and CT images are acquired when the marker position m...

The store-operated calcium-release-activated calcium current, I (CRAC), is a major mechanism for calcium entry into non-excitable cells. I (CRAC) refills calcium stores and permits sustained calcium signalling. The relationship between inositol 1,4,5-trisphosphate receptor (InsP(3)R)-containing stores and I (CRAC) is not understood. A model of global InsP(3)R store depletion coupling with I (CR...

One challenge in studying the second messenger inositol(1,4,5)-trisphosphate (InsP₃) is that it is present in very low amounts and increases only transiently in response to stimuli. To identify events downstream of InsP₃, we generated transgenic plants constitutively expressing the high specific activity, human phosphatidylinositol 4-phosphate 5-kinase Iα (HsPIPKIα). PIP5K is the enzyme that sy...

Inositol 1,4,5-trisphosphate receptors (InsP(3)Rs) modulate Ca(2+) release from intracellular Ca(2+) store and are extensively expressed in the membrane of endoplasmic/sarcoplasmic reticulum and Golgi. Although caffeine and 2-aminoethoxydiphenyl borate (2-APB) have been widely used to block InsP(3)Rs, the use of these is limited due to their multiple actions. In the present study, we examined a...

Striated muscle represents one of the best models for studies on Ca(2+) signalling. However, although much is known on the localisation and molecular interactions of the ryanodine receptors (RyRs), far less is known on the localisation and on the molecular interactions of the inositol trisphosphate receptors (InsP(3)Rs) in striated muscle cells. Recently, members of the Homer protein family hav...

The efficacy of muscarinic-receptor agonists for stimulation of inositol phosphate formation and Ca2+ mobilization in intact 1321N1 human astrocytoma cells is correlated with their capacity for formation of a GTP-sensitive high-affinity binding complex in membranes from these cells [Evans, Hepler, Masters, Brown & Harden (1985) Biochem. J. 232, 751-757]. These observations prompted the proposal...

Cells aggressively defend adenosine nucleotide homeostasis; intracellular biosensors detect variations in energetic status and communicate with other cellular networks to initiate adaptive responses. Here, we demonstrate some new elements of this communication process, and we show that this networking is compromised by off-target, bioenergetic effects of some popular pharmacological tools. Trea...