Fig. 8. CF50 is present in an 450 kDa complex in CM. CM was prepared from Ax2 and smlA^– cells, and concentrated 10-fold. (A) The material was size-fractionated on a sieving gel column, and the fractions were assayed for CF50 by western blotting. The 50 kDa CF50 band from both wild-type and smlA^– CM elutes at approximately 450 kDa; a 30 kDa band eluting below 66 kDa is also present in the smlA^– CM. The elution position of size markers is shown at the bottom. (B) CM from Ax2 and cf50^– cells was similarly size fractionated and the fractions were assayed for countin by western blotting. As previously observed, countin in Ax2 CM elutes at 450 kDa (Brock and Gomer, 1999), while the countin in cf50^– CM elutes primarily at a lower molecular weight. The position of size markers is the same as in A.