St. Jude儿童研究医院研究者发现，ABCB6蛋白对于一种分子的产生起着关键作用，这种分子对于红细胞携带氧，肝细胞破坏毒素以及细胞从摄取营养物质后排放能量方面发挥重要的作用。
??St. Jude研究者指出，ABCB6蛋白寄宿在“能量动力站”--线粒体的外膜；它将一种重要的生命分子--比咯滋质输入线粒体。这些研究结果已经在线出版在《自然》杂志上。
??在线粒体内部，比咯紫质被转换成亚铁血红素。亚铁血红素是血红蛋白携带氧的血素部分。同时也是某些破坏毒素的肝脏酶的关键组分；在线粒体中，亚铁血红素被称为是氧气产生能量分子的“呼吸链”酶。
??ABCB6蛋白定位和功能的新发现为比咯紫质是如何进入线粒体转变成亚铁血红素这样一个长期疑惑作了很好的解答。St. Jude药学成员John Schuetz博士认为，比咯紫质带负电荷，所以能进入线粒体内部，一个磁场的两个负极应该互相排斥，但一个负电荷分子是如何进入一个负电荷环境不是很清楚。John Schuetz等的研究工作表明，ABCB6只是通过抓住比咯紫质分子，将其带入线粒体，从而克服了以上问题。
??“我们指出，ABCB6和亚铁血红素、比咯紫质水平之间的动态联系有助于调节亚铁血红素的产量。” Schuetz说。研究小组发现，线粒体膜上ABCB6蛋白的增加导致细胞产生更多的亚铁血红素必须的比咯紫质。他们之间这种联系的任何中断都可能会因为亚铁血红素或者比咯紫质的改变而给细胞带来严重的问题。
??有了这些新的研究资料，将有助于研究者更好地从分子水平研究某些疾病，对疾病的成因了解更多，从而可能知道如何阻止或治疗这些疾病。有一类疾病是皮肤性卟啉病，这是由于比咯紫质的增加引起皮肤起水疱，在太阳下就会肿胀；急性的卟啉病激发胸，腹部，四肢或背部的痛疼，麻痹，抽筋和个性的变化以及精神的紊乱等神经问题。Schuetz认为，如果卟啉病人吃了某些干扰其系统的镇定剂和其他药物，病人会突然急性发作，所以Schuetz的工作为‘生产亚铁血红素生化途径的中断是如何引起各种疾病’提供了一个总的描绘。
英文原文：
ABCB6 is key to production of heme in hemoglobin
Investigators at St. Jude Children's Research Hospital have discovered that a protein called ABCB6 plays a central role in production of a molecule that is key to the ability of red blood cells to carry oxygen, of liver cells to break down toxins, and of cells to extract energy from nutrients.
The St. Jude investigators showed that ABCB6 is lodged within the outer membrane of the cell's energy powerhouse called the mitochondria; and that it ferries into mitochondria a type of molecule called a porphryin, a molecule essential for life. A report on these results appears in the advanced online publication of Nature.
Inside the mitochondrion, porphyrins are converted to heme. Heme is the oxygen-carrying part of the red blood cell molecule called hemoglobin, as well as a critical part of certain liver enzymes that break down toxins, and so-called "respiratory chain" enzymes in mitochondria that use oxygen to produce energy-rich molecules.
The discovery of the location and function of ABCB6 solved the long-standing riddle of how porphyrins get into mitchondria so they can be used to make heme, said John Schuetz, PhD, a member of St. Jude Pharmaceutical Sciences. "Porphyrins are negatively charged and so is the inside of mitochondria," Schuetz said. "So it wasn't clear how a negatively charged molecule could get into a negatively charged environment when it should have been repulsed--like two negative poles of a magnet pushing each other apart. Our work showed that ABCB6 overcomes that problem by simply grabbing porphyrin molecules and pulling them in.
"We showed that there is a dynamic relationship between ABCB6 and the levels of heme and porphyrin that helps to regulate the production of heme," Schuetz said. The team found that the increase in ABCB6 in mitochondrial membranes caused the cells to make more porphyrin, the building block of heme. "Any disruption of this relationship can cause serious problems in the cell by altering levels of heme or porphyrins," Schuetz said.
Armed with this new information, researchers will be better able to study certain diseases at the molecular level and learn more about their causes and perhaps how to prevent or treat them. One such group of diseases is cutaneous porphyria, a buildup of porphyrins that causes the skin to blister and swell in sunlight; and acute porphoryia, a nerve problem that triggers pain in the chest, abdomen, limbs or back, as well as paralysis, cramping and personality changes or mental disorders. "Also, people with porphyria can suffer sudden, acute attacks if they take certain tranquilizers and other drugs that interfere with this system," Schuetz said. "So our work contributes to the overall picture of how disruption of the biochemical pathway of heme production can cause a variety of serious diseases."
