UBR4 (ubiquitin protein ligase E3 component n-recognin 4) interacts with retinoblastoma protein in the nucleus and functions as a chromatin scaffold. In the cytoplasm, UBR4 regulates cytoskeletal dynamics and membrane morphogenesis. It is important for formation of integrin-mediated ruffled membrane and cell survival. UBR4 forms an E2-E3 complex with RAD6 (ubiquitin-conjugating enzyme E2) and KCMF1 (potassium channel modulatory factor 1). The complex regulates lysosome-mediated degradation of N-end rule substrates. UBR4 associates with human papillomavirus type 16 (HPV-16) E7 oncoprotein and participates in anchorage-independent growth in cancer cells.
