THAP domain-containing protein 4 is a protein that in humans is encoded by the THAP4 gene. It is one of twelve known members of the thanatos-associated protein (THAP) Family of proteins. Members of this family share a conserved N-terminal THAP domain as well as a conserved zinc-binding module that likely mediates DNA binding. THAP4 also has a structurally distinct C-terminal region that binds heme, which is unique among human THAP proteins.
THAP4 is considered a distinctive member of the THAP protein family because the composition of its domain suggests that it has DNA binding capacity as well as the ability to sense or at least respond to some molecules through its heme binding domain. This combination of features has caused THAP4 to be theorized to be a potential signaling-responsive regulatory protein, however its exact biological targets and regulatory roles remain to be experimentally observed. In addition to this, comparative sequence analysis shows has shown that the C-terminal region of THAP4 is relatively conserved across some species of mammals, which supports the idea that this domain serves an important cellular function rather than being a species specific or rapidly evolving structural addition.