F8A1
Description
The F8A1 (coagulation factor VIII associated 1) is a protein-coding gene located on chromosome X.
The F8A1 gene encodes a 40-kDa protein known as the huntingtin-associated protein (HAP40). It is located within intron 22 of the factor VIII gene and is transcribed in the opposite direction. The gene is conserved in mice, suggesting a functional role. Interestingly, F8A1 is transcribed abundantly in a variety of cell types, unlike the factor VIII gene. A portion of intron 22, containing F8A1, is duplicated outside of the factor VIII gene (F8A2, F8A3). While the specific function of F8A1 remains unknown, its conservation across species suggests a significant role.
F8A1, along with its closely related gene copies F8A2 and F8A3, acts as an effector molecule for RAB5A, a protein involved in the movement of early endosomes within cells. This interaction mediates the recruitment of HTT (huntingtin protein) to early endosomes by RAB5A. The complex formed by HTT, F8A1/F8A2/F8A3, and RAB5A promotes the attachment of early endosomes to actin filaments, while inhibiting their attachment to microtubules. This leads to a decrease in the movement of early endosomes within the cell.
F8A1 is also known as DXS522E, F8A, HAP40.
