Beamer L J, Fischer D, Eisenberg D
Biochemistry Department, University of Missouri-Columbia, 65211, USA.
Protein Sci. 1998 Jul;7(7):1643-6. doi: 10.1002/pro.5560070721.
In mammals, a family of four lipid binding proteins has been previously defined that includes two lipopolysaccharide binding proteins and two lipid transfer proteins. The first member of this family to have its three-dimensional structure determined is bactericidal/permeability-increasing protein (BPI). Using both the sequence and structure of BPI, along with recently developed sequence-sequence and sequence-structure similarity search methods, we have identified 13 distant members of the family in a diverse set of eukaryotes, including rat, chicken, Caenorhabditis elegans, and Biomphalaria galbrata. Although the sequence similarity between these 13 new members and any of the 4 original members of the BPI family is well below the "twilight zone," their high sequence-structure compatibility with BPI indicates they are likely to share its fold. These findings broaden the BPI family to include a member found in retina and brain, and suggest that a primitive member may have contained only one of the two similar domains of BPI.
在哺乳动物中，先前已定义了一个由四种脂质结合蛋白组成的家族，其中包括两种脂多糖结合蛋白和两种脂质转移蛋白。该家族中第一个确定其三维结构的成员是杀菌/通透性增加蛋白（BPI）。利用BPI的序列和结构，以及最近开发的序列-序列和序列-结构相似性搜索方法，我们在包括大鼠、鸡、秀丽隐杆线虫和盖氏双脐螺在内的多种真核生物中鉴定出了该家族的13个远亲成员。尽管这13个新成员与BPI家族的4个原始成员中任何一个之间的序列相似性远低于“模糊区域”，但它们与BPI的高度序列-结构兼容性表明它们可能共享其折叠结构。这些发现拓宽了BPI家族的范围，使其包括在视网膜和大脑中发现的一个成员，并表明一个原始成员可能仅包含BPI两个相似结构域中的一个。
