CHASE6 was originally described as a two-partite extracellular (periplasmic) sensor domain found in histidine kinases and HD-GYP-type c-di-GMP-specific phosphodiesterases [1] and assigned to COG4250 in the COG database. Subsequently, its N-terminal part has been described as a separate DICT (DIguanylate Cyclases and Two-component systems) domain (PF10069) (Aravind L., Iyer LM, Anantharaman V. (2010) Natural history of sensor domains in the bacterial signalling systems. In: Sensory Mechanisms in Bacteria: Molecular Aspects of Signal Recognition ((Spiro S, Dixon R, eds)), pp. 1-38. Caister Academic Press, Norfolk, UK). The current entry contains only the C-terminal part of the original CHASE6 domain described in [1], which is found primarily in cyanobacteria.

1: Common extracellular sensory domains in transmembrane receptors for diverse signal transduction pathways in bacteria and archaea. Zhulin IB, Nikolskaya AN, Galperin MY; J Bacteriol 2003;185:285-294. PMID:12486065