The evolution of transmembrane helix kinks and the structural diversity of G protein-coupled receptors.

ABSTRACT: One of the hallmarks of membrane protein structure is the high frequency of transmembrane helix kinks, which commonly occur at proline residues. Because the proline side chain usually precludes normal helix geometry, it is reasonable to expect that proline residues generate these kinks. We observe, however, that the three prolines in bacteriorhodopsin transmembrane helices can be changed to alanine with little structural consequences. This finding leads to a conundrum: if proline is not required for helix bending, why are prolines commonly present at bends in transmembrane helices? We propose an evolutionary hypothesis in which a mutation to proline initially induces the kink. The resulting packing defects are later repaired by further mutation, thereby locking the kink in the structure. T

SUBMITTER: Yohannan S 

PROVIDER: S-EPMC327124 | biostudies-literature | 2004 Jan

REPOSITORIES: biostudies-literature