A DIMERIZATION MOTIF FOR TRANSMEMBRANE ALPHA-HELICES

Specific helix-helix interactions inside lipid bilayers guide the fold ing and assembly of many integral membrane proteins and their complexe s. We report here a pattern of 7 amino acids (LIxxCVxxGVxxT) which whe n introduced into several hydrophobic transmembrane alpha-helices prom otes their specific dimerization. Dimerization is driven by interactio ns that are specific, dominated by the helix-helix interface, and invo lve no potentially ionizabIe groups. The motif may provide a useful to ol for the functional analysis of such interactions in a variety of sy stems. Further, since this particular motif is rare, whilst specific h elix association is not, many other such motifs may exist, which could permit sorting within complex membranes as well as guiding folding an d oligomerization.