On the mechanism of sensory transduction in bacterial chemotaxis

Sensory transduction in bacterial chemotaxis is beginning to be understood at the molecular level. At the receptor end, we have some considerable knowledge about the molecular properties of chemoreceptors. At the effector end, we know that flagella rotate and that the direction of rotation is determined by attractants and repellents, although we do not yet know the molecular features of the motor and the gear shift. Between the receptors and the effectors is a system for integrating the sensory transduction, which somewhow involves methylation of membrane proteins and possibly a change in membrane potential, but further details of how the mechanism works remain to be elucidated. It seems to us likely that the facts and concepts learned from a study of sensory transduction in bacteria can be applied to answering questions about transduction mechanisms in eukaryotic cells. Examples include the following: How do sensory stimuli produce their effects in sensory receptor cells? How do neurotransmitters act at receptors of postsynaptic cells to produce the variety of effects possible (changes in membrane potential, in secretion, in contraction, etc.)? How do hormones interact with their receptors to bring about various responses?