Showing papers by "Michael J. Berridge published in 2007"
TL;DR: In this paper, a mechanism for Ca2+ oscillations with particular emphasis on the way agonist concentration regulates oscillator frequency is described, and the main idea is that the InsP3 receptors are sensitized to release Ca 2+ periodically by cyclical fluctuations of Ca 2 + within the lumen of the endoplasmic reticulum.
Abstract: InsP3 has two important functions in generating Ca2+ oscillations. It releases Ca2+ from the internal store and it can contribute to Ca2+ entry. A hypothesis has been developed to describe a mechanism for Ca2+ oscillations with particular emphasis on the way agonist concentration regulates oscillator frequency. The main idea is that the InsP3 receptors are sensitized to release Ca2+ periodically by cyclical fluctuations of Ca2+ within the lumen of the endoplasmic reticulum. Each time a pulse of Ca2+ is released, the luminal level of Ca2+ declines and has to be replenished before the InsP3 receptors are resensitized to deliver the next pulse of Ca2+. It is this loading of the internal store that explains why frequency is sensitive to external Ca2+ and may also account for how variations in agonist concentration are translated into changes in oscillation frequency. Variations in agonist-induced entry of external Ca2+, which can occur through different mechanisms, determine the variable rates of store loading responsible for adjusting the sensitivity of the InsP3 receptors to produce the periodic pulses of Ca2+. The Ca2+ oscillator is an effective analogue-to-digital converter in that variations in the concentration of the external stimulus are translated into a change in oscillator frequency.
134 citations
TL;DR: Ca 2+ signalling systems are adapted to control cellular processes over a wide time domain for processes such as exocytosis, muscle contraction, metabolism and gene transcription and fertilization and cell proliferation.
Abstract: A large number of cellular processes are controlled by Ca 2+ signalling. The versatility of this signalling system depends on the existence of an extensive Ca 2+ signalling toolkit from which cells can assemble cell-specific Ca 2+ signalsomes that are precisely suited to deliver the signals to control their particular functions. The spatial and temporal properties of such cell-specific Ca 2+ signals are a particularly important feature of this diversity. Ca 2+ signalling systems are adapted to control cellular processes over a wide time domain for processes such as exocytosis (microseconds), muscle contraction (milliseconds), metabolism and gene transcription (seconds to minutes) and fertilization and cell proliferation (hours).
10 citations