Reactions of DDAb3 and DDAb16 with constructs 1 and 4 (Western blot). (Left) Both antibodies recognize construct 1 (srGPIIIa) in the presence of quinine. However, DDAb3 fails to recognize construct 4 (A50S, R62Q, D66A). (Middle) DDAb3 and DDAb16 fail to recognize either construct in the absence of quinine. (Right) Blot with monoclonal AP5 confirms that adequate quantities of both constructs were present for antibody detection.