Fig 2. SctA is a major constituent of secreted dense bodies.

(A) D. discoideum cells were pelleted by centrifugation at 600 x g (pellet P6) and the supernatant (S6) was sequentially subjected to centrifugations at 15’000 and 100’000 x g. The corresponding supernatants (S15, S100) and pellets (P15, P100) resuspended in an equivalent volume were diluted in reducing sample buffer and separated on a 15% acrylamide gel. Equal volume of samples were loaded except for P6 that was diluted 1/10. The main proteins were revealed by silver staining. (B) The same amount of the 15 000 x g pellet was resuspended in reducing (+DTT) or non reducing (-DTT) sample buffer and analyzed by SDS-PAGE and Coomassie staining. Molecular weights (in kDa) are indicated, as well as the SctA protein (arrowheads).