Western blotting using Fluorescein conjugated anti-beta-Galactosidase antibody shows a band at ~117 kDa (lanes 1-3) corresponding to 60 ng, 30 ng and 15 ng, respectively of beta-Galactosidase present in partially purified preparations (arrowhead). Lane 4 shows no cross reactivity with proteins present in a non-specific control E.coli lysate. Proteins were resolved on a 4-20% Tris-Glycine gel by SDS-PAGE and transferred to nitrocellulose and blocking using Blocking Buffer for Fluorescent Western Blotting. The membrane was probed with fluorescein conjugated anti-b-Galactosidase diluted to 1:10000. Reaction occurred for 2 hours at room temperature. Molecular weight estimation was made by comparison to a prestained MW marker in lane M. Fluorescence image was captured using the VersaDoc Imaging System developed by BIO-RAD. Other detection systems will yield similar results.