Signaling Across Membranes—A One and a Two and a …

The usually accepted mechanisms for transduction of a signal across the membrane require that the receptor exist as a dimer. New results in this issue by Tatsuno et al . ( p. 423 ) and Gardina et al . ( p. 425 ) show that the bacterial chemotaxis receptor Tar can actually function quite well if its intracellular domain is monomeric. In his Perspective, Stock describes how current assumptions about the role of dimers in receptor signal transduction may be too simple, and that at least sometimes, monomeric forms of the receptor may be the functionally relevant molecule.