Component of the SCF (SKP1-CUL1-F-box protein) E3 ubiquitin ligase complex, which mediates the ubiquitination and subsequent proteasomal degradation of target proteins. The SCF complex plays a crucial role in regulating response to auxin and is essential for growth and development. Through the RING-type zinc finger, seems to recruit the E2 ubiquitination enzyme, to the complex and brings it into close proximity to the substrate. Promotes the neddylation of CUL1. Protein modification; protein ubiquitination. Part of SCF complexes, which consist of a SKP1-related protein, a cullin, a RBX protein and a F-box protein. Part of a SCF complex with ASK1 or ASK2 and CUL1. Part of a SCF complex with CUL1 and TIR1. Interacts with CUL1 and CUL4. Component of the CUL4-RBX1-CDD complex. A number of isoforms are produced. According to EST sequences. Widely expressed. Expressed in shoot, siliques, meristem, flowers, floral buds, open flowers, leaves, stems, roots, germinal seeds and seedlings in dark. Expressed at a higher level in tissues containing actively dividing cells. The RING-type zinc finger domain is essential for ubiquitin ligase activity. It coordinates an additional third zinc ion. Belongs to the RING-box family.