As part of the axonemal inner dynein arm complex plays a central role in ciliary beat (PubMed:30060180). Expressed in sperm flagellum, it is required for sperm motility (By similarity). Dyneins are microtubule-based molecular motors possessing ATPase activities that can convert the chemical energy of ATP into relative sliding between adjacent microtubule doublets to generate ciliary bending (PubMed:30060180). Part of the axonemal inner dynein arm complex that consists of at least two heavy chains and a number of intermediate and light chains (PubMed:30060180). Interacts with DNAI4 (PubMed:30060180). 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 (By similarity). Belongs to the dynein heavy chain family. Truncated N-terminus.