VapB-1 and VapC-1 heterodimerize in vivo . 86-028NP vapB-1 or vapC-1 was fused to the LexA DNA binding domain (DBD) in the vectors pSR658 or pSR659, resulting in pDD866 or pDD868, respectively. Reciprocally, vapC-1 or vapB-1 was also fused to the LexA DBD in the vectors pSR658 or pSR659, resulting in pDD859 or pDD867, respectively. Each pair was co-transformed into the reporter strain SU202 and the amount of heterodimerization was quantitated by β-galactosidase activity assays (n = 3 in triplicate). Data are expressed as mean ± SD.