SDS-PAGE analysis of different cell extracts from wild-type (WT) and 630NP (NP) strains of S. mutans: bead-beaten SDS-boiling extracts (A), 4% SDS extracts (B), bead-beaten Tris extracts (C), and surface-associated fractions extracted with 0.2% (wt/vol) Zwittergent in PBS (D). Following SDS-PAGE, proteins were either stained with Coomassie blue (top) or transferred onto a nitrocellulose membrane and subjected to Western blotting using an anti-630D1 polyclonal antiserum at the dilution of 1:350 (bottom). Lane M, size marker.