Contrin, the human homologue of a germ-cell Y-box-binding protein: Cloning, expression, and chromosomal localization

Inactivation of germ-cell-specific molecules essential for the production o f functional spermatozoa could lead to attractive new means for male contra ception. The mouse protein MSY2 is the mammalian homologue of a class of Xe nopus DNA/RNA-binding proteins needed for the transcription of testis-speci fic genes and for translational repression (masking) of paternal mRNAs. In this report. we describe the human homologue for MSY2, Contrin. Sequence an alysis of Contrin cDNAs predicts a protein highly similar to its mouse and Xenopus germ-cell Y-box protein homologues with a cold shock domain and fou r basic/ aromatic islands. Contrin is highly basic and is rich in the amino acids arginine and proline. It contains seven putative casein kinase 2 pho sphorylation sites and three putative protein kinase C phosphorylation site s, suggesting that Contrin could be highly phosphorylated in viva. The pred icted protein sequence contains two nuclear localization signals, consisten t with its predicted role of shuttling between nucleus and cytoplasm. Contr in maps to human chromosome 17p11.2-13.1.. By the criteria of northern and western blotting, Contrin appears to be testis specific and distinct from o ther mammalian Y-box-binding proteins. We predict that inactivation of Cont rin function in mammalian germ cells would prevent the formation of functio nal male gametes.