Membrane Proteins. The Amino Acid Composition of Membrane-Penetrating Segments

The overall amino acid composition of membrane-penetrating segments of trans-membrane proteins can be well reproduced by computer simulation of ‘evolution’ of hydrophobic protein segments, with selection operating only on the hydrophobicity of the sequence. This substantiates the idea that the specific amino acid sequence is relatively less important than the preservation of an overall hydrophobic character in such segments, and furnishes an example of macromolecular evolution where the evolutionary process can be quantitatively mimicked on the computer.