Co-IP of BAX and BAK using anti-BAX IgGs from different vendors using anti-ms / anti-rb IgG VHH Agarose (mrIGa). Tested IgGs include such of rabbit and mouse origin with IgG1 and IgG2b subtypes. 5 µg of respective IgG was spiked into HEK293T cell lysate derived from 0.5x10^7 cells. 1% of Input (IN) and 25% of bound (B) fraction was loaded onto an SDS-PAGE gel. For Western Blot analysis BAX was detected using a polyclonal rb IgG (PTG: 50599-2-Ig) (1:2000) labeled using the FlexAble HRP Antibody Labeling Kit for rabbit IgG. This allows a clean detection of BAX, without interfering signals of IgG heavy and light chains derived from the spiked rabbit antibodies. The presence of BAK co-precipitated with BAX was tested using a polyclonal  rb IgG (PTG 29552-1-AP) 1:2000, labeled with FlexAble HRP. While all IgGs allowed for efficient IP of BAX, BAK was absent in the case of the primary antibody from vendor D, possibly due to the BAX:BAK interaction interface being masked by this particular IgG.