Molecular Playground/CLOCK:BMAL1 heterodimer complex: Difference between revisions

The <scene name='60/609802/Clock_bmal1/1'>CLOCK:BMAL1 heterodimer complex</scene> is a vital regulatory component of the circadian rhythm protein regulation system. CLOCK (''Circadian Locomotor Output Cycles Kaput'') and BMAL1 (''Brain and muscle Arnt-like protein-1'') are <scene name='60/609802/Bhlh_ex/1'>the basic helix-loop-helix</scene> PER-ARNT-SIM (bHLH-PAS) proteins. The structure highlighted in yellow is a portion of bHLH structure in CLOCK. They are the main transcriptional activators in the mammalian circadian mechanism.<ref>DOI: 10.1126/science.280.5369.1564</ref> The binding between CLOCK and BMAL1 involves the N-terminal bHLH, PAS-A and PAS-B domains of both proteins. Each domain binds to its corresponding equivalent domain in the other protein. Though both proteins contain the same types of domains with similar primary amino acid sequences in each, the overall heterodimer is surprisingly asymmetrical due to differences in the spatial orientation of the domains in each protein. Since this heterodimer complex involves the binding of all of the major domains in both participating proteins, the overall binding affinity is very high.