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 resul t of the sharing of gene products through their intercellular bridges. This movement of molecules among haploid cells is crucial for the pro duction of spermatozoa since numerous essential proteins are encoded o n sex chromosomes. Testis-brain RNA-binding protein (TB-RBP) is a sing le-stranded DNA- and RNA-binding protein prominent in the nuclei and c ytoplasm of specific stages of differentiating male germ cells. Here w e present evidence that TB-RBP moves from the nucleus to the cytoplasm and through intercellular bridges of male germ cells. Based on its RN A-binding capabilities, we propose a role for TB-RBP in the distributi on of equal amounts of mRNAs in haploid male germ cells. (C) 1998 Acad emic Press.