first PDC (PhoQ/DcuS/CitA) domain of methyl-accepting chemotaxis proteins and similar domains
Members of this subfamily display varying domain architectures but all contain double PDC (PhoQ/DcuS/CitA) sensor domains. This model represents the first PDC domain of Methyl-accepting chemotaxis proteins (MCPs), Histidine kinases (HKs), and other similar domains. Many members contain both HAMP (HK, Adenylyl cyclase, MCP, and Phosphatase) and MCP domains, which are signalling domains that interact with protein partners to relay a signal. MCPs are part of a transmembrane protein complex that controls bacterial chemotaxis. HK receptors are part of two-component systems (TCS) in bacteria that play a critical role for sensing and adapting to environmental changes. Typically, HK receptors contain an extracellular sensing domain flanked by two transmembrane helices, an intracellular dimerization histidine phosphorylation domain (DHp), and a C-terminal kinase domain, with many variations on this theme. In the case of HKs, signals detected by the sensor domain are transmitted through DHp to the kinase domain, resulting in the phosphorylation of a conserved histidine residue in DHp; phosphotransfer to a conserved aspartate in its cognate response regulator (RR) follows, which leads to the activation of genes for downstream cellular responses.
Jiyao W et al.(2023). "The conserved domain database in 2023.",