Prm3, the fourth gene in the mouse protamine gene cluster, encodes a conserved acidic protein that affects sperm motility.
Grzmil P, Boinska D, Kleene KC, Adham I, Schlüter G, Kämper M, Buyandelger B, Meinhardt A, Wolf S, Engel W. Biol Reprod. 2008 Jun; 78(6):958-67. Epub 2008 Feb 6.