Novel RING Finger Protein OIP1 Binds to Conserved Amino Acid Repeats in Sperm Tail Protein ODF11

Abstract

Outer dense fibers (ODFs) and the fibrous sheath (FS) are unique structures of the mammalian sperm tail. Recently, progress has been made in the molecular cloning of ODF and FS proteins, and because of this, questions addressing the morphogenesis and underlying protein network that make up sperm tail structures and their function can now be addressed. Using the N-terminal leucine zipper motif of the major ODF protein ODF1, we had previously isolated interacting proteins Odf2, Spag4, and Spag5. We report here a yeast two-hybrid strategy to isolate a novel rat testicular protein, OIP1, that binds to the evolutionarily conserved Cys-Gly-Pro repeats in the C-terminus of ODF1. OIP1 is expressed in round spermatids as well as in spermatocytes and several somatic tissues, albeit at a lower level. No expression was detectable in epididymis, heart, and smooth muscle. OIP1 protein localizes to the sperm tail in a pattern expected for an ODF1-interacting protein. OIP1 belongs to the family of RING finger proteins of the H2 subclass. Deletion of the putative RING motif significantly decreased binding to ODF1. Genomic analysis of rat Oip1 and Oip1 homologs indicates that Oip1 is highly conserved. Oip1 is subject to differential splicing and alternative polyadenylation events. It is interesting that Oip1 mRNAs have been reported that lack the exon encoding the putative RING finger.

Haplo-deficiency of ODF1/HSPB10 in mouse sperm causes relaxation of head-to-tail linkage

“…However, binding partners that mediate the connection to the nucleus at the implantation fossa via the basal plate are currently not known. Among the identified ODF1-interacting proteins, none is located at a position to possibly function in sperm head-tail coupling (Shao et al 1999, Bhullar et al 2003, Zarsky et al 2003, Zhang et al 2004, Fitzgerald et al 2005. The basal plate and its intrinsic proteins are crucial when looking for the head-tail coupling apparatus.…”

Moving to the beat: a review of mammalian sperm motility regulation

“…The successful cloning of several genes that code for keratin-like intermediate filament ODF proteins provides support for this hypothesis (Gastmann et al 1993;Morales et al 1994;Hoyer-Fender et al 1995Kim et al 1995;Burmester and Hoyer-Fender 1996;Kierszenbaum et al 1996;Tres and Kierszenbaum 1996;Brohmann et al 1997;Shao et al 1997;Schalles et al 1998;Zarsky et al 2003). To date, none of these ODF-specific genes has been targeted for mutation and, so, the true role of these proteins, and the role of the ODFs, remains somewhat speculative.…”

The Small Heat Shock Protein ODF1/HSPB10 Is Essential for Tight Linkage of Sperm Head to Tail and Male Fertility in Mice

“…The scaffold of the ODF fiber may thus be structured by the two main ODF proteins, ODF1 and ODF2 (46). Other ODF1 interacting proteins are SPAG4, KLC3 (kinesin light chain 3), OIP1 (ODF1-interacting protein), and SPAG5 (4,18,52,63). SPAG4 is located in the transient manchette and associated with the axoneme in elongating spermatids and epididymal sperm.…”