Figure 2. Isolation of knockout clones deficient for components of the MHC-I antigen presentation pathway. A.

Identifying knockout clones by PCR. A schematic representation of the β2m, tapasin and TAP2 knockout clones identified by PCR from 96 single cell clones from the HLA-B^low selected population. Screening a relatively low number of single cell clones is sufficient to identify knockout cells representing the relevant target genes found in a screen. B. The gene-trap insertions result in a loss of gene expression. The knockout clones were analyzed for HLA-A2, β2m, tapasin and TAP2 expression by RT-PCR. C. Knockout of genes involved in the MHC-I pathway impairs cell surface expression of MHC-I molecules. The β2m, HLA-A2, tapasin and TAP2 knockout clones were labeled for the indicated proteins and analyzed by flow cytometry.