Probable substrate-specific adapter of an E3 ubiquitin-protein ligase complex which mediates the ubiquitination and subsequent proteasomal degradation of target proteins (PubMed:14528312). Seems to regulate expression levels and/or subnuclear distribution of TOP1, via an unknown mechanism (By similarity). May play a role in mesenchymal differentiation where it promotes myogenic differentiation and suppresses adipogenesis (By similarity). Protein modification; protein ubiquitination. Interacts (via C-terminus) with TOP1 (PubMed:11818025). Interacts with TRIM5 isoform Delta (PubMed:12878161). Interacts with CUL3 (PubMed:14528312). Localizes to punctate or elongated cytoplasmic bodies. Ubiquitous; highest levels in testes, heart and skeletal muscle.