Outer Dense Fiber Protein 3, Sperm Tails (ODF3)

ODF3 is a component of sperm flagella outer dense fibers, which add stiffness, elastic recoil, and protection against shearing forces during sperm movement.The deduced 254-amino acid protein contains 6 pro-gly-pro repeats. Human and mouse ODF3 share 93% amino acid identity. Northern blot analysis of several mouse tissues detected a 1.2-kb Odf3 transcript only in testis. Cell fractionation of mouse testis showed Odf3 transcript restricted to germ cells, with no expression in Leydig or Sertoli cells. Western blot analysis detected mouse Odf3 at an apparent molecular mass of 32 kD. Immunolocalization revealed Odf3 localized in the flagella of the elongated spermatids and along the entire length of the tail in mature sperm. Odf3 was resistant to treatment with nonionic detergents and coextracted with the cytoskeletal core proteins of the mouse sperm tail.