Sequence specificity in the dimerization of transmembrane .alpha.-helixes

摘要: While several reports have suggested a role for helix-helix interactions in membrane protein oligomerization, there are few direct biochemical data bearing on this subject. Here, using mutational analysis, we show that dimerization of the transmembrane alpha-helix glycophorin A detergent environment is spontaneous and highly specific. Very subtle changes side-chain structure at certain sensitive positions disrupt association. These occur approximately every 3.9 residues along helix, consistent with their comprising interface closely fit transmembranous supercoil alpha-helices. By contrast other reported cases between helices, set interfacial case contains no polar groups. Amino acids aliphatic side chains define much interface, indicating precise packing helices may provide energy highlight potential general importance specific hydrophobic anchors integral proteins.