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CLPH, a Novel Casein Kinase 2-Phosphorylated Disordered Protein, Is Specifically Associated with Post-Meiotic Germ Cells in Rat Spermatogenesis.

Authors: Calvel, P  Kervarrec, C  Lavigne, R  Vallet-Erdtmann, V  Guerrois, M  Rolland, A  Chalmel, F  Jegou, B  Pineau, C 
Citation: Calvel P, etal., J Proteome Res. 2009 Mar 9.
Pubmed: (View Article at PubMed) PMID:19271754
DOI: Full-text: DOI:10.1021/pr900082m

In a recent proteomic study of rat spermatogenesis, we identified CLPH (for Casein-Like PHosphoprotein), a new testis-specific protein expressed exclusively in post-meiotic germ cells. In situ hybridization showed that the CLPH transcript was mainly present in round spermatids, whereas the protein was specifically detected by immunohistochemistry in elongated spermatids and in residual bodies. Electron microscopy showed the protein to be mostly cytoplasmic, but also frequently associated with the mitochondrial inner membrane during the last steps of spermatid differentiation. The Clph gene was found to be present solely in mammalian genomes, in a chromosomal region syntenic to the mammalian cluster of secretory calcium-binding phosphoprotein (SCPP) genes. CLPH has several distinctive properties in common with SCPPs: calcium overlay experiments showed that CLPH was a calcium-binding protein, whereas trypsin digestion assay, circular dichroism and fluorescence experiments demonstrated its intrinsically disordered structure. We also showed that CLPH was phosphorylated in vitro and in vivo by casein kinase 2, an enzyme critical for spermatid elongation. Given the specific and strong production of CLPH during rat spermiogenesis, together with the particular biochemical properties of this protein, we suggest that CLPH is involved in the extremely complex structural rearrangements occurring in haploid germ cells during spermiogenesis.


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CRRD Object Information
CRRD ID: 2306007
Created: 2009-03-18
Species: All species
Last Modified: 2009-03-18
Status: ACTIVE


RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.