Dyneins are multisubunit, high molecular weight ATPases that interact with microtubules to generate force by converting the chemical energy of ATP into the mechanical energy of movement. Axonemal Dynein motors contain one to three non-identical heavy chains and cause a sliding of microtubules in the axonemes of cilia and flagella in a mechanism necessary for cilia to beat and propel the cell. DNAH1 (dynein heavy chain 1, axonemal), also known as heat shock regulated protein 1 or ciliary dynein heavy chain 1, is a 4,330 amino acid protein consisting of at least two heavy chains and several intermediate and light chains. Mutations in the gene encoding DNAH1 may be a cause of primary ciliary dyskinesia, also known as Kartagener Syndrome, which is characterized by chronic recurrent respiratory infections due to defective cilia action in the respiratory tract. There are three isoforms of DNAH1 that exist as a result of alternative splicing events.