F-actin-based Ca signaling-a critical comparison with the current concept of Ca signaling.
A short comparative survey on the current idea of Ca signaling and the alternative concept of F-actin-based Ca signaling is given. The two hypotheses differ in one central aspect, the mechanism of Ca storage. The current theory rests on the assumption of Ca-accumulating endoplasmic/sarcoplasmic reticulum-derived vesicles equipped with an ATP-dependent Ca pump and IP3- or ryanodine-sensitive channel-receptors for Ca-release. The alternative hypothesis proceeds from the idea of Ca storage at the high-affinity binding sites of actin filaments. Cellular sites of F-actin-based Ca storage are microvilli and the submembrane cytoskeleton. Several specific features of Ca signaling such as store-channel coupling, quantal Ca release, spiking and oscillations, biphasic and "phasic" uptake kinetics, and Ca-induced Ca release (CICR), which are not adequately described by the current concept, are inherent properties of the F-actin system and its dynamic state of treadmilling.
Lange
Klaus
K
Kladower Damm 258, Berlin, Germany. piotr222@zedat.fu-berlin.de
Gartzke
Joachim
J
D000199:Actins / Q000378:metabolism*; D000818:Animals; D020013:Calcium Signaling / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D008871:Microvilli / Q000648:ultrastructure; D008954:Models, Biological; D009218:Myosins / Q000378:metabolism
D000199:Actins; D009218:Myosins