Fig. 5. Distribution of SphB1 in B.pertussis cellular fractions. Proteins of BPSM (WT), BPLC5 (ΔsphB1) and BPLC7 (S→A sphB1) were separated between supernatants (Sup., lanes 1–3) and cell lysates (lanes 4–6). These lysates were further fractionated between soluble and insoluble fractions by ultracentrifugation (lanes 7–9 and 10–12, respectively). The insoluble fractions were then extracted with Triton X-100 to separate the Triton-soluble and -insoluble fractions (lanes 13–15 and 16–18, respectively). Twenty microlitres of 10-fold concentrated culture supernatants were loaded in lanes 1–3. The proteins loaded in lanes 4–12 were extracted from 0.4 OD₆₀₀ equivalents of bacterial cells, while the proteins loaded in lanes 13–18 were extracted from 1.2 OD₆₀₀ equivalents of bacterial cells. Samples were analysed by immunoblotting using the anti-SphB1 antiserum. pSphB1 and SphB1 denote the precursor and mature forms of the protein, respectively. The masses in kDa of the molecular markers are shown at the left.