de Meis Leopoldo
Instituto de Ciências Biomédicas, Departamento de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Cidade Universitária, RJ 21941-590, Brazil.
J Biol Chem. 2003 Oct 24;278(43):41856-61. doi: 10.1074/jbc.M308280200. Epub 2003 Aug 11.
In this report a sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) was identified in rats brown adipose tissue. Electrophoretic analysis of brown fat microssomal protein yields a 110-kDa band that is reactive to SERCA 1 antibody but is not reactive to SERCA 2 antibodies. Nevertheless, the kinetics properties of the brown fat SERCA differ from the skeletal muscle SERCA 1 inasmuch they manifest a different Ca2+ affinity and a much higher degree of ATPase/Ca2+ uncoupling. A SERCA enzyme is not found in white fat. Fatty acids promoted Ca2+ leakage from brown fat vesicles. The heat released during ATP hydrolysis was -24.7 kcal/mol when a Ca2+ gradient was formed across the vesicles membrane and -14.4 kcal/mol in the absence of a gradient. The data reported suggest that in addition to storing Ca2+ inside the endoplasmic reticulum, the Ca2+-ATPase may represent a source of heat production contributing to the thermogenic function of brown adipose tissue.
在本报告中，在大鼠棕色脂肪组织中鉴定出一种肌浆/内质网Ca2 + -ATP酶（SERCA）。对棕色脂肪微粒体蛋白进行电泳分析，得到一条110 kDa的条带，该条带与SERCA 1抗体反应，但不与SERCA 2抗体反应。然而，棕色脂肪SERCA的动力学特性与骨骼肌SERCA 1不同，因为它们表现出不同的Ca2 +亲和力和更高程度的ATP酶/Ca2 +解偶联。在白色脂肪中未发现SERCA酶。脂肪酸促进了棕色脂肪囊泡中的Ca2 +泄漏。当在囊泡膜上形成Ca2 +梯度时，ATP水解过程中释放的热量为-24.7 kcal/mol，在没有梯度的情况下为-14.4 kcal/mol。报告的数据表明，除了在内质网中储存Ca2 +外，Ca2 + -ATP酶可能是产热的一个来源，有助于棕色脂肪组织的产热功能。
