The DNA/RNA-binding protein, TB-RBP, moves from the nucleus to the cytoplasm and through intercellular bridges in male germ cells.

The genetically haploid spermatids are functionally diploid as a result of the sharing of gene products through their intercellular bridges. This movement of molecules among haploid cells is crucial for the production of spermatozoa since numerous essential proteins are encoded on sex chromosomes. Testis-brain RNA-binding protein (TB-RBP) is a single-stranded DNA- and RNA-binding protein prominent in the nuclei and cytoplasm of specific stages of differentiating male germ cells. Here we present evidence that TB-RBP moves from the nucleus to the cytoplasm and through intercellular bridges of male germ cells. Based on its RNA-binding capabilities, we propose a role for TB-RBP in the distribution of equal amounts of mRNAs in haploid male germ cells.