Tagging allows faithful tracing of expression and enhances biochemical detection of Ran Binding Protein 9 in vivo

The lack of tools to reliably detect RanBP9 in vivo has significantly hampered progress in understanding the biological functions of this scaffold protein. We report here the generation of a novel mouse strain, RanBP9-TT, in which the endogenous protein is fused with a double (V5-HA) epitope tag at the C-terminus. We show that the double tag does not interfere with the essential functions of RanBP9. Opposite to RanBP9 constitutive knock-out (KO) animals, both male and female RanBP9-TT mice are viable, fertile and do not show any obvious phenotype. The presence of the tags allows unequivocal detection of RanBP9 in tissues both by IHC and WB. Importantly, immunoprecipitation and mass spectrometry analyses reveal that the tagged protein pulls down known interactors of wild type RanBP9. In summary, we report here the generation of a new mouse in which RanBP9 expression and interactions can be reliably studied by the use of commercially available atag antibodies and overcome some of the existing limitations in the study of this protein in vivo.