title: Surface recognition elements of membrane protein oligomerization.
abstract: Although certain membrane proteins are functional as monomeric polypeptides, others must assemble into oligomers to carry out their biological roles. High-resolution membrane protein structures provide a valuable resource for examining the sequence features that facilitate-or preclude-assembly of membrane protein monomers into multimeric structures. Here we have utilized a data set of 28 high-resolution alpha-helical membrane protein structures comprising 32 nonredundant polypeptides to address this issue. The lipid-exposed surfaces of membrane proteins that have reached their fully assembled and functional biological units have been compared with those of the individual subunits that build quaternary structures. Though the overall amino acid composition of each set of surfaces is similar, a key distinction-the distribution of small-xxx-small motifs-delineates subunits from membrane proteins that have reached a functioning oligomeric state. Quaternary structure formation may therefore be dictated by small-xxx-small motifs that are not satisfied by intrachain contacts.
authors.affiliation: Division of Molecular Structure and Function, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8.
authors.forename: Arianna
authors.initials: A
authors.lastname: Rath
authors.forename: Charles M
authors.initials: CM
authors.lastname: Deber
mesh_terms: D020816:Amino Acid Motifs; D030562:Databases, Protein; D019281:Dimerization; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D013499:Surface Properties
chemical_list: D008565:Membrane Proteins; D021122:Protein Subunits