The osmosensory transporter coiled coil is a C-terminal domain found in various bacterial osmoprotective transporters, such as ProP, Proline/betaine transporter, Proline permease 2 and the citrate proton symporters. It adopts an antiparallel coiled-coil structure, and is essential for osmosensory and osmoprotectant transporter function [1].

1: Solution structure of the C-terminal antiparallel coiled-coil domain from Escherichia coli osmosensor ProP. Zoetewey DL, Tripet BP, Kutateladze TG, Overduin MJ, Wood JM, Hodges RS; J Mol Biol. 2003;334:1063-1076. PMID:14643666