AP-2 beta (Activating enhancer-binding protein 2-beta; also TFAP2B) is a 52kD member of the AP-2 family of transcription factors. It is primarily a fetal-expressed protein, being found in renal and skin epithelial cells, as well as neuroblasts plus cells of the facial mesenchyme. In adults, AP-2 beta is expressed in renal epithelium. Human AP-2 beta is 460aa in length. It contains a transactivation domain (aa41-131), a DNA-binding motif (aa132-298) and a C-terminal dimerization region (aa299-439). SUMOylation occurs on Lys21, adding 15kD of MW in SDS-PAGE. AP-2 beta both homodimerizes, and heterodimerizes with AP-2 alpha and -2 gamma. Dimers appear important for facial and limb development.