Substrate-recognition component of the SCF(FBXL3) 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 (PubMed:17463251, PubMed:23452855, PubMed:27565346). The SCF(FBXL3) complex mainly acts in the nucleus and mediates ubiquitination and subsequent degradation of CRY1 and CRY2 (PubMed:17463251, PubMed:23452855, PubMed:27565346). Activity of the SCF(FBXL3) complex is counteracted by the SCF(FBXL21) complex (PubMed:23452855). Protein modification; protein ubiquitination. Part of the SCF (SKP1-CUL1-F-box) E3 ubiquitin-protein ligase complex SCF(FBXL3) composed of CUL1, SKP1, RBX1 and FBXL3 (By similarity). Interacts with CRY1 and CRY2 (phosphorylated) (PubMed:17463251). Interacts with HDAC3 (By similarity). Interacts with KDM8 (By similarity). Predominantly nuclear. Widely expressed. Undergoes autophagy-mediated degradation in the liver in a time-dependent manner. The disease is caused by variants affecting the gene represented in this entry.