Component of an E3 ubiquitin ligase complex that plays a central role in blue light-dependent circadian cycles. Acts as a blue light photoreceptor, due to the presence of FMN, that mediates light-regulated protein degradation of critical clock components by targeting them to the proteasome complex. The SCF(ADO2) E3 ubiquitin ligase complex is involved in the regulation of circadian clock-dependent processes including the transition to flowering time, hypocotyl elongation, cotyledons and leaf movement rhythms. APRR1/TOC1 and APRR5 seem to be substrates of the SCF(ADO2) complex. ADO2 interacts with ADO3 and export it to cytoplasmic speckles, preventing the interaction of ADO3 with CDF1. Ubiquitination of ADO2 is not involved in this recruitment. Protein modification; protein ubiquitination. Self-associates. Interacts (via Kelch repeats) with AD03, CDF1, CDF2 and CDF3. Interacts with GI, ADO1, SKP1A/ASK1, SKP1B/ASK2, SKP1C/ASK3, SKP1D/ASK4, SKP1E/ASK5, SKP1K/ASK11, SKP1N/ASK14, SKP1TA/ASK20A, SKP1TB/ASK20B, APRR1, APRR5, DI19 and COL1. Weakly expressed in seedlings, root tips, stems, leaves, flowers, young siliques, sepals and seeds. FMN binds covalently to cysteine after exposure to blue light and is reversed in the dark. Accumulation of ADO3 protein during the morning period but no effect on flowering time. 'Adagio' means slowly in Italian. Belongs to the ADAGIO family. Truncated N-terminus. Truncated N-terminus.