Involved in spermiogenesis. Plays a role in the proper organization of axoneme in sperm flagella, but not in cilia, by recruiting DNAH1 and DNALI1 to flagellum. {ECO:0000250, ECO:0000269|PubMed:40146200}. This is the function of Ensembl gene identifier ENSG00000174844 (DNAH12, dynein axonemal heavy chain 12).