Molecular cloning of Odf3 encoding a novel coiled-coil protein of sperm tail outer dense fibers

The outer dense fibers (ODF) are the main cytoskeletal structures of the sp erm tail found in animals with internal fecundation. They consist of at lea st 14 polypeptides from which only a few are identified due to difficulties in isolation of the protein components. Here we report the isolation and m olecular characterization of Odf3, encoding a novel protein of rat sperm OD E Odf3 is transcribed in testes and more specifically in spermatids but it is also expressed in epididymides and brain suggesting a possible involveme nt in building of the cellular cytoskeleton. Odf3 encodes a putative protei n of similar to 110 kDa. Secondary structure predictions indicated that ODF 3 is a coiled-coil protein. The identification of coiled-coil proteins as c onstituents of outer dense fibers reveals a model for ODF formation. Mol. R eprod. Dev. 61: 102-112, 2002. (C) 2002 Wiley-Liss, Inc.