Huntingtin-associated protein 1

Huntingtin-associated protein 1 (HAP1) is a protein which in humans is encoded by the HAP1 gene. This protein was found to bind to the mutant huntingtin protein (mHtt) in proportion to the number of glutamines present in the glutamine repeat region.

Huntington's disease (HD), a neurodegenerative disorder characterized by loss of striatal neurons, is caused by an expansion of a polyglutamine tract in the HD protein huntingtin. This gene encodes a protein that interacts with huntingtin, with two cytoskeletal proteins (dynactin and pericentriolar autoantigen protein 1), and with a hepatocyte growth factor-regulated tyrosine kinase substrate (HGS). The interactions with cytoskeletal proteins and a kinase substrate suggest a role for this protein in vesicular trafficking or organelle transport.