【摘要】 生物作用广泛的细胞信使主要是Ca²⁺和cAMP。Ca²⁺在生物体内通过其受体蛋白,即钙调节蛋白发挥功能。钙调节蛋白可分为两类:一类主要在胞外起作用,如与凝血有关的钙蛋白;另一类在胞内起作用,如多功能的钙媒介蛋白。后者具有特殊的、但非专一的钙结合区,正常生理条件下能与Ca²⁺可逆性结合。形成的钙媒介蛋白·Ca²⁺络合物可直接激活靶蛋白或酶,也可通过靶蛋白间接调节磷酸化和去磷酸化,从而发挥多种生物功能。更多还原

【Abstract】 Ca2+ and cAMP are ubiquitous intracellular messengers. The message of Ca2+ is relayed by receptor proteins, mainly calcium regulated proteins. Calcium regulated proteins can be divided into two classes according to their localization in living tissues: one exerts their calcium dependent functions extracellularly , such as γ-carboxyglutamic acid containing proteins involved in the regulation of blood clotting; the other is Ca2+ modulated proteins, in which a striking example is calmodulin, postulated to be the major intracellular Ca2+ signal transducer. Calmodulin harbors four Ca2+-binding domains which reversibly bind Ca2+ to form an active protein-Ca2+ complex, whose activity is regulted by the cellular flux of Ca2+ . The active complex operates in two different ways: one is on the target enzymestor proteins) directly, and the other is through the target protein, allowing it to (?) calmodulin regulated protein kinases and phosphatasets). The molveular basis of calcium action, and in particular, the modulation of calmodulin are reviewed here.更多还原