Abstract
The mechanism of gene regulation is discussed from a kinetic viewpoint. Genes are expressed/replicated by complex multi-step reactions but only a few steps determine regulatory responses. Such steps are often attributed to binding of a regulatory protein to a specific nucleic acid. Several binding mechanisms could cause a sensitive or abrupt change in the amount of substances regulated. Cooperative binding is most frequently found among these mechanisms. The time required for equilibrium deserves emphasis. Binding equilibrium is not always attained and the ultrasensitivity of cooperative binding could be lost because of slow equilibrium. One-dimensional diffusion of a regulatory protein along nucleic acid is sometimes needed for a rapid binding.
