The use of BirA-BAP system to study the effect of US2 and US11 on MHC class I heavy chain in cells

•A method to study protein turn-over in cells is described.•The assay is based on biotinylation of a tagged protein in cells expressing biotin ligase.•Degradation of MHC proteins mediated by HCMV US2 and US11 could be observed by using this method.•The assay can be used to study protein traffic and turn-over in cells.