Synaptonemal complex protein SYCP3 of the rat: evolutionarily conserved domains and the assembly of higher order structures.

SYCP3 is a major structural protein component of vertebrate synaptonemal complexes as well as an important determinant of male fertility, at least in mammals. The elucidation of SYCP3 polymerization properties would provide important information towards our understanding as to how synaptonemal complexes are assembled and disassembled during meiotic prophase. To this end we have investigated the possible contribution of different SYCP3 domains to the assembly of higher order structures. We observed that the evolutionarily conserved domains of the molecule (i.e. the alpha-helix together with the two flanking motifs CM1 and CM2) are not only necessary but also sufficient for SYCP3 polymerization. The relevance of these results for reproduction biology is underscored by recent studies showing that the deletion of the very end of the alpha-helix and CM2 leads to meiosis disruption and infertility in humans. 2007 S. Karger AG, Basel