The var2csa-uORF directs protein expression to a specific cellular localization associated with the ER. (A and B) Immunofluorescence microscopy of parasites expressing the constructs pV-GB and puORF-GFP (schematically shown above each panel). BSD was labeled with an anti-GFP antibody (green) and the ER with a specific antibody against Pf39=ERC (red). Nuclei were stained with DAPI (blue). Scale bars: 2 mm (total of 158 GFP positive, pV-GB expressing parasites all showed diffused cytoplasmic localization; 37/41 GFP positive, puORF-GFP expressing parasites showed distinct focus associated with the ER). while the protein which was not fused to the uORF is cytosolic (A), the fusion of the uORF sequence significantly changes its subcellular location. The protein can be visualized around the nucleus as distinct foci associated with the ER (B).

Fastman Y, Assaraf S, Rose M, Milrot E, Basore K, Arasu BS, Desai SA, Elbaum M, Dzikowski R. An upstream open reading frame (uORF) signals for cellular localization of the virulence factor implicated in pregnancy associated malaria. Nucleic Acids Res. 2018 [Epub ahead of print]