This domain is found at the N-terminal end of Circadian clock protein KaiA from Synechococcus elongatus and similar bacterial proteins. KaiA is essential for circadian timekeeping. This protein organised into two domains. This entry represents the a pseudo-receiver domain, which has a similar fold with that of bacterial response regulators, with an alpha-beta structure [1-5].

1: Structure and function from the circadian clock protein KaiA of Synechococcus elongatus: a potential clock input mechanism. Williams SB, Vakonakis I, Golden SS, LiWang AC; Proc Natl Acad Sci U S A. 2002;99:15357-15362. PMID:12438647

2: Crystal structure of circadian clock protein KaiA from Synechococcus elongatus. Ye S, Vakonakis I, Ioerger TR, LiWang AC, Sacchettini JC; J Biol Chem. 2004;279:20511-20518. PMID:15007067

3: Crystal structure of the redox-active cofactor dibromothymoquinone bound to circadian clock protein KaiA and structural basis for dibromothymoquinone's ability to prevent stimulation of KaiC phosphorylation by KaiA. Pattanayek R, Sidiqi SK, Egli M; Biochemistry. 2012;51:8050-8052. PMID:23020633

4: Protein-Protein Interactions in the Cyanobacterial Circadian Clock: Structure of KaiA Dimer in Complex with C-Terminal KaiC Peptides at 2.8 A Resolution. Pattanayek R, Egli M; Biochemistry. 2015;54:4575-4578. PMID:26200123

5: Structures of the cyanobacterial circadian oscillator frozen in a fully assembled state. Snijder J, Schuller JM, Wiegard A, Lossl P, Schmelling N, Axmann IM, Plitzko JM, Forster F, Heck AJ; Science. 2017;355:1181-1184. PMID:28302852