nos promoter sequences drive expression of a Tag:MCP-mCherry fusion protein. A Tag:NLS(SV40-largeT) nuclear localization signal is present at the N-terminal end of the open reading frame (ORF) and a Tag:FLAG epitope is present at the C-terminal end of the ORF. The portion of the fs(1)K10 3'UTR which stabilises germline transcripts and restricts them to nurse cells is also present. FlyBase curator comment: in the presence of a mRNA tagged with Tag:MS2 (an RNA stem loop to which Tag:MCP binds), the Tag:MCP-mCherry fusion protein can bind to this tagged mRNA, allowing its localization within the cell to be studied. In the absence of a Tag:MS2-tagged mRNA (or when unbound), the Tag:MCP-mCherry fusion protein will be targeted to the nucleus due to the presence of the Tag:NLS(SV40-largeT) tag.