The gene HAP1 (huntingtin-associated protein 1) is a bifunctional enzyme th at functions as a DNA repair enzyme as well as in redox activation of transcription factors. It binds to the Huntingtonμs disease (HD) protein huntingtin in a polyglutamine length-dependent manner. It associates with huntingtin via the cytoskeletal proteins dynactin and pericentriolar autoantigen protein 1 forming coiled-coils. It plays a role in vesicle trafficking by facilitating interactions among cytoskeletal, vesicular and motor proteins. It is an apurinic/apyrimidinic (AP) site-specific DNA repair endonuclease th at removes the AP sites produced naturally or by cytotoxic drugs and radiation. It also has RNAse H activity and controls the redox state of certain proto-oncogene products, such as the transcription factor c-Jun. The HAP1 protein is a candidate for pathology associated with HD.
