Sperm Antigen 6 Is the Murine Homologue of the Chlamydomonas reinhardtii Central Apparatus Protein Encoded by the PF16 Locus1

Abstract

A cDNA encoding sperm antigen 6 (Spag6), the murine homologue of the Chlamydomonas reinhardtii PF16 protein-a component of the flagella central apparatus-was isolated from a mouse testis cDNA library. The cDNA sequence predicted a 55.3-kDa polypeptide containing 8 contiguous armadillo repeats with 65% amino acid sequence identity and 81% similarity to the Chlamydomonas PF1 protein. An antipeptide antibody generated against a C-terminal sequence recognized a 55-kDa protein in sperm extracts and localized Spag6 to the principal piece of permeabilized mouse sperm tails. When expressed in COS-1 cells, Spag6 colocalized with microtubules. The Spag6 gene was found to be highly expressed in testis and was mapped using the T31 radiation hybrid panel to mouse chromosome 16. Mutations in the Chlamydomonas PF16 gene cause flagellar paralysis. The presence of a highly conserved mammalian PF16 homologue (Spag6) raises the possibility that Spag6 plays an important role in sperm flagellar function.

Conserved and specific functions of axoneme components in trypanosome motility

“…Identity was 30-40% between human and trypanosome orthologues, with the exception of PF16, which was more than 60% identical. These values are in the same range as between Chlamydomonas and human flagellar genes (Pennarun et al, 1999;Sapiro et al, 2000). By contrast, the PFR genes, initially identified in T. brucei (Deflorin et al, 1994;Schlaeppi et al, 1989), are exclusively present in trypanosomatid and euglenid genomes so far with no counterpart in other species (Kohl and Bastin, 2005).…”

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

“…Scale bars in electron micrographs are 50 nm. the homologue of the Chlamydomonas PF16 locus encoding a protein of the central apparatus of the axoneme (Neilson et al 1999, Sapiro et al 2000, 2002. Easy sperm decapitation was also reported in mice with Oaz-t (Oaz3) deficiency, the testis-specific ornithine decarboxylase antizyme, presumably by affecting the local concentration of polyamines (Tokuhiro et al 2009).…”

TheChlamydomonas PF6Locus Encodes a Large Alanine/Proline-Rich Polypeptide That Is Required for Assembly of a Central Pair Projection and Regulates Flagellar Motility

“…Additional sequence information concerning the human cDNA will be needed to determine whether this is the human version of the PF6 gene; however, its expression in the testis is consistent with a potential flagellar function. Interestingly, recent studies have demonstrated that several of the central pair polypeptides first characterized in Chlamydomonas have closely related (i.e., 60 -70% identity) vertebrate homologues Lefebvre, 1996, 1997;Neilson et al, 1999;Sapiro et al, 2000).…”

“…Additional sequence information concerning the human cDNA will be needed to determine whether this is the human version of the PF6 gene; however, its expression in the testis is consistent with a potential flagellar function. Interestingly, recent studies have demonstrated that several of the central pair polypeptides first characterized in Chlamydomonas have closely related (i.e., 60 -70% identity) vertebrate homologues Lefebvre, 1996, 1997;Neilson et al, 1999;Sapiro et al, 2000).The large size of the PF6 protein (Ͼ238 kDa) and its sedimentation characteristics on sucrose density gradients (ϳ12.6S) suggest that the PF6 polypeptide may serve as a molecular scaffold for the assembly of components associated with the 1a projection on the C1 microtubule. The pf6 mutations result in the absence of the C1-1a projection (Figures 1 and 2) and the loss of two or more polypeptides that appear to cosediment with the PF6 protein ( Figure 9B).…”