The goal of this proposal is to understand the mechanisms that govern localization of Vg1 RNA on the Xenopus oocyte. Previous experiments in Schnapp's lab have shown that this localization requires the presence of at least one copy each of four different repeats present in the 3'UTR of the mRNA. A five nucleotide repeat UUCAC (E2) appears to play a major role and is the focus of much of this grant. Schnapp has identified a protein, vera, that binds to the VgLE, most likely by direct physical association with the E2 repeat. Because Vera is an ER associated protein, Schnapp proposes that it plays a role in localizing Vg1RNA to the ER. Schnapp has also succeeded in isolating a RNP particle containing the Vg1 localization element (VgLE). All four VgLE repeat types are required for the VgLE's association in the particle. This contrasts with the earlier observation that only three (E1,E2,E4) are required for association with vera protein, suggesting in turn that the latter is not sufficient for particle assembly.