Another way to analyze electrophoretically separated serum proteins is by "immunoblotting", in which different Ig isotypes are detected by use of specific labelled antibodies. The first lane represents all serum proteins visualized with a blue dye (as in conventional serum electrophoresis). The second lane shows the location of IgG, which constitutes the bulk of the gamma-globulin peak. The presence of both kappa (lane 5) and lambda (lane 6, very weak) light chains is demonstrated within this IgG. A pale band representing IgA is seen in the beta-globulin region (lane 3). IgM, which may be localized across the beta- and gamma-globulin regions, is not visible in this image.