Force generating protein of cilia required for sperm flagellum motility (PubMed:11371505). Produces force towards the minus ends of microtubules. Dynein has ATPase activity; the force-producing power stroke is thought to occur on release of ADP (By similarity). Required in spermatozoa for the formation of the inner dynein arms and biogenesis of the axoneme (By similarity). Consists of at least two heavy chains and a number of intermediate and light chains. Mice are viable and show no malformations; however, homozygous males are infertile, due to inability of spermatozoa to move from the uterus into the oviduct. Spermatozoa show decreased motility. In addition, tracheal beating frequency is reduced. Belongs to the dynein heavy chain family.