TAR DNA-binding protein 43 (TDP-43), is a cellular protein which in humans is encoded by the TARDBP gene. Recent advances in research have identified an ubiquinated protein that is commonly found in the majority of ALS cases. In healthy nerve cells this protein, called TDP-43, is typically localized to the nucleus. The nucleus is where the cell stores the information required to make proteins needed for normal cell function (growth, aspiration, division). Biochemical studies have shown that the accumulated TDP-43 located in the affected nerve cells contain abnormal variants of the protein. The accumulation of abnormal TDP-43 in this area of the cell is speculated to cause a loss in cellular function due to the absence of normal TDP-43 in the nucleus, thus impairing the viability of the affected nerve cells. In affected nerve cells, such as the case with ALS, TDP-43 is only found in the cytoplasm. The cytoplasm is located outside of the nucleus and is the primary site for chemical activity in the cell.