Protein L is a 36 kDa immunoglobulin-binding protein isolated from the bacteria Peptostreptococcus magnus. Unlike Protein A and Protein G, which bind to the Fc region of immunoglobulins (antibodies), Protein L binds antibodies through light chain interactions. Protein L binds a wider range of antibody classes than Protein A or G. Protein L binds to representatives of all antibody classes, including IgG, IgM, IgA, IgE and IgD.
