Figure 1.

Common domain arrangements in histidine kinases. (A) Simple transmembrane histidine kinases with two membrane-spanning segments (black boxes). The sensor component is periplasmic, and a cytoplasmic “linker” domain precedes the receptor kinase domain. (B) Approximate spacing of conserved, short sequence motifs characteristic of histidine kinases (5). The H block motif includes the histidine autophosphorylation site. (C) Location of many high likelihood coiled coils in the cytoplasmic linker domain before the H block motif. (D) Common domain pattern in longer kinases. Two coiled coils are predicted, occurring before the H block motif and shortly after the final transmembrane segment.