Force generating protein component of the outer dynein arms (ODAs) in the sperm flagellum. 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. Involved in sperm motility; implicated in sperm flagellar assembly. Consists of at least two heavy chains and a number of intermediate and light chains. Detected in sperm tail, with almost exclusive localization to the principal piece. Also detected in the cytoplasm of primary spermatocytes. Isoform 1 and/or isoform 2 are expressed in spermatocytes and mature sperm (at protein level). Testis-specific. Accumulates exclusively in mid to late spermatocytes. Dynein heavy chains probably consist of an N-terminal stem (which binds cargo and interacts with other dynein components), and the head or motor domain. The motor contains six tandemly-linked AAA domains in the head, which form a ring. A stalk-like structure (formed by two of the coiled coil domains) protrudes between AAA 4 and AAA 5 and terminates in a microtubule-binding site. A seventh domain may also contribute to this ring; it is not clear whether the N-terminus or the C-terminus forms this extra domain. There are four well-conserved and two non-conserved ATPase sites, one per AAA domain. Probably only one of these (within AAA 1) actually hydrolyzes ATP, the others may serve a regulatory function. Homozygous knockout male mice are sterile due to diminished sperm movement (PubMed:32619401). Sperm flagella show disorganized microtubules and outer dense fibers resulting in significantly higher rates of abnormal flagella (PubMed:32619401). May be due to an intron retention. Belongs to the dynein heavy chain family. Truncated N-terminus.