Ca2+-calmodulin tubulin kinase system and its role in mediating the Ca2+ signal in brain.

Abstract

Publisher Summary Ca 2+ plays a major role in the function of nervous tissue. Calmodulin is a major Ca 2+ receptor protein in brain and other tissues and has been shown to modulate the effects of Ca 2+ on several important enzyme systems. Ca 2+ -calmodulin protein phosphorylation, especially the tubulin kinase system, provides an important mechanism for regulating synaptic activity. Tubulin has been identified as a major substrate for the calmodulin kinase system and this major cytoskeletal protein may provide an important insight into how Ca 2+ dynamically alters synaptic function. The phosphorylation of tubulin by the Ca 2+ kinase results in a marked allosteric alteration in the tubulin molecule resulting in the formation of very stable tubulin aggregates that form microfilaments. Thus, Ca 2+ can produce marked changes in the physicochemical properties of tubulin through the action of the calmodulin tubulin kinase system. This system provides an attractive biochemical model for converting the Ca 2+ signal into molecular change. The evidence for the role of Ca 2+ kinases and specifically the tubulin kinase system in synaptic modulation is discussed in the chapter.