Interaction of DNA polymerase beta with GRIP1 during meiosis.

DNA polymerase beta (pol beta) is an essential enzyme that has been shown to localize as discrete foci to the synaptonemal complex during meiosis in the mouse. To identify proteins that associate with pol beta during meiosis, we employed the yeast two-hybrid screen. Here we show that a multiple PDZ domain-containing protein, the glutamate receptor interacting protein 1 (GRIP1), interacts specifically with pol beta. The PDZ domain-containing proteins, including GRIP1, act as scaffolds to promote rapid and localized biochemical events that require the interaction of multiple proteins. GRIP1 localizes to discrete foci on meiotic bivalents of both spermatocyte and oocyte nuclei, and colocalizes with pol beta. Together, these findings provide evidence that GRIP1 interacts with pol beta during meiosis. Our findings are consistent with the possibility that GRIP1 acts as a scaffold to promote interaction between proteins that function during meiosis.