Long description

The figure consists of two parts, Figures 12a and b, that illustrate double immunolabelling of the cytoskeleton.

Figure 12a: step 1. Two different unlabelled ‘primary’ antibody molecules are bound to different antigens. A schematic diagram shows antigen A (dark-blue circle) and antigen B (light-blue circle) attached to a common surface below. Primary antibody 1: An inverted yellow Y-shaped primary antibody has circular terminal grooves on each branch, and the tail end has two small rectangular lateral projections. The circular terminal groove of the right branch of antibody 1 is bound to antigen A. Primary antibody 2: An inverted yellow Y-shaped primary antibody has circular terminal grooves on each branch, and the tail end has two small triangular lateral projections. The circular terminal groove of the right branch of antibody 2 is bound to antigen B. Step 2. Two secondary antibody molecules are labelled with different fluorophores. Secondary antibodies type 1: Two inverted light-green Y-shaped secondary antibody molecules have rectangular terminal grooves on each branch. The tail end of each antibody has two small triangular lateral projections bound complementary on the left to a fluorophore label (green star). Secondary antibodies type 2: Two inverted light-pink Y-shaped secondary antibody molecules have triangular terminal grooves on each branch. The tail end of each antibody has two small triangular lateral projections bound complementary to a fluorophore label (red star). Step 3: Labelled ‘secondary’ antibody molecules bind to specific primary antibody molecules. The rectangular grooves of labelled ‘secondary’ antibodies type 1 are bound to the lateral rectangular projections of primary antibody 1. Secondary antibodies are bound laterally to the green fluorophore labels. Primary antibody 1 is bound to antigen A. The triangular grooves of labelled ‘secondary’ antibodies type 2 are bound to the lateral triangular projections of primary antibody 2. Secondary antibodies are bound laterally to the red fluorophore labels. Primary antibody 2 is bound to antigen B.

Figure 12b: a fluorescence micrograph shows double immunolabelling of the cytoskeleton (actin and tubulin) in two cells using two primary and secondary antibodies. A central nucleus is shown in blue surrounded by tubulin, followed by actin (cell periphery). Each cytoskeletal structure is detected by a different secondary antibody. Actin is labelled with the first fluorophore label, green fluorescence. Tubulin is labelled second fluorophore label, red fluorescence. The scale bar equals 10 micrometres.