Structural Study of Transmembrane Domain of Band 3 Protein

本课题研究了带3蛋白的结构和功能，并提出了多跨多位膜蛋白的新概念。这种蛋白质的跨膜结构域可以分为三类，即，跨膜肽的亲水环连接（第1类）、通过肽-肽相互作用嵌入的部分（第2类）和通过肽-脂质相互作用嵌入的部分（第3类）。多位膜蛋白的2类肽被发现稳定地存在于脂质双层中，而没有肽-脂质相互作用，这被认为是跨膜片段所必需的。第3类肽相当于双位膜蛋白的单跨段。采用蛋白酶切法、带3蛋白化学修饰法和无细胞转录/翻译实验系统对跨膜肽进行了分类

In this project, we have investigated the band 3 protein structure and function and introduced a novel concept in multi-spanning polytopic membrane proteins revealed by the study on band 3 protein. The transmembrane domain of such proteins can be divided into three categories, that is, hydrophilic loops connecting of transmembrane peptides (category 1), portions being embedded by the peptide-peptide interactions (category 2) and portions being embedded by the peptide-lipid interactions (category 3). Category 2 peptides of polytopic membrane proteins were found to stably reside in the lipid bilayer without peptide-lipid interactions which had been thought to be essential for transmembrane segments. Category 3 peptide is equivalent to the single-spanning segment of a bitopic membrane protein. Three different experiments, that is, a proteolytic digestion method, a chemical modification on band 3 protein and a cell free transcription/translation experiment system, were used to categorize the transmembrane peptides