Putative F-box/LRR-repeat protein 21 (FBXL21P)

Substrate-recognition component of the SCF(FBXL21) E3 ubiquitin ligase complex involved in circadian rhythm function. Plays a key role in the maintenance of both the speed and the robustness of the circadian clock oscillation.

The SCF(FBXL21) complex chiefly acts in the cytosol and mediates ubiquitination of CRY proteins (CRY1 and CRY2), leading to CRY proteins stabilization. The SCF(FBXL21) complex counteracts the activity of the SCF(FBXL3) complex and shields CRY proteins from degradation.