脑红蛋白和细胞红蛋白：携氧蛋白质家族2个新成员

脑红蛋白(neuroglobin, Ngb)和细胞红蛋白(cytoglobin, Cygb)是新发现的2个携氧蛋白家族的成员.脑红蛋白主要存在于脑中，而细胞红蛋白在全身各个组织都含有，它们和另外2个携氧蛋白——血红蛋白和肌红蛋白的同源性<25%，但它们在种属之间的同源性很高(>95%).脊椎动物脑红蛋白基因定位于14q24，细胞红蛋白基因定位于17q25，都含有4个外显子和3个内含子.2种蛋白在生理条件下含有6个配位键，不同于血红蛋白和肌红蛋白的5个配位键结构.这2种新蛋白和氧都具有很高的亲和力，在缺氧条件下其基因及蛋白表达都有明显的提升，对细胞的存活有一定保护作用.对于脑红蛋白和细胞红蛋白的功能研究，有助于更好地了解机体氧代谢和氧利用过程，并为临床在缺氧损伤时的治疗提供新的观点和途径.

Neuroglobin and Cytoglobin: Two New Members of Globin Family

Neuroglobin and cytoglobin are two recently discovered members of the vertebrate globin family. Neuroglobin is predominantly expressed in the brain while cytoglobin is expressed in many different tissues. They share little amino acid sequence similarity with hemoglobin or myoglobin (<25%), but in human and mouse they are 95% identical. Neurogloin gene is located on chromosome 14q24 and cytoglobin maps to chromosome 17q25. Both of them have four exons and three introns. They have a common feature of being hexacoodinated under deoxy conditions which is different from pentacoordinated structure of hemoglobin and myoglobin. These two new proteins have high oxygen affinity and are up-regulated under hypoxia conditions which suggested to be protective for cell survival. The study on neuroglobin and cytoglobin is important for our future understanding of brain oxygen metabolism and utilization. It will provide new sights and approaches for ischemic injury therapy.