Structure Prediction of Intrinsic Membrane Proteins

膜蛋白具有许多重要的生物学功能。然而，它们的结构几乎不为人所知。因此，本研究的目的是阐明膜蛋白的结构形成机制，并设计一种结构预测的方法。本研究的结果可概括如下。(1)可溶性蛋白和膜蛋白的氨基酸序列比较表明，疏水性信息足以区分这两类蛋白。(2)变性实验表明，跨膜螺旋之间通过氢键结合。也就是说，光谱测量表明，酒精破坏了细菌视紫红质的三级结构，这是一种典型的膜蛋白，氢键被特别破坏。(3)具有7个跨膜螺旋的膜蛋白氨基酸序列中氢键残基的分布与三级结构形成的氢键机制是一致的。从而明确了膜蛋白结构预测的原理。

Membrane proteins have many important biological functions. However, their structure is hardly known. Therefore, the aim of this research project is to clarify the mechanism of structure formation of membrane proteins and to devise a method for the structure prediction. The results of this research may be summarized as follows. (1) The comparison between the amino acid sequences of soluble and membrane proteins revealed that the information of hydrophobicicity is enough for the distinction between the two types of proteins. (2) Transmembrane helices is bound with each other by hydrogen bonds, as inferred from denaturation experiments. Namely, spectroscopic measurements showed that alcohols destroyed the tertiary structure of bacteriorhodopsin, a typical membrane protein, and that hydrogen bonds were specifically destroyed. (3) The distribution of hydrogen bonding residues in the amino acid sequences of membrane proteins having seven transmembrane helices was compatible with the hydrogen bonding mechanism of the tertiary structure formation. Consequently, the principle of the structure prediction of membrane proteins has become clear by this research project.