Simple model to study insertion of a protein into a membrane

A simple coarse grained model on a two-dimensional lattice is presented to elucidate the main effects ruling the insertion of a protein into a polar e nvironment such as a lipidic membrane. The amino acids are divided into two classes (hydrophobic or polar), and they behave differently according to t heir surroundings. In aqueous solution the hydrophobic amino acids are forc ed to minimize contacts with water, whereas in the apolar environment all t he amino acids try to aggregate regardless to their specificity. The lattic e is employed in order to perform exact calculations and to generate a fict itious protein data bank. Despite the simplicity of the model, some morphol ogical features of the proteinlike lattice structures obtained by our model are compatible with the observed phenomenology of transmembrane proteins. These results seem to corroborate the hypothesis that the number of classes into which the amino acids can be divided that correctly describe the phen omena may be extremely low. [S1063-651X(99)08212-4].