Fig. 4

Cross-linking of G-protein coupled receptors (GPCR) by the corresponding functional autoantibodies (GPCR-AAB); the key event for receptor mediated signaling after receptor binding of GPCR-AAB is illustrated [21] Using the bioassay of spontaneously beating cultured neonatal rat cardiomyocytes, the chronotropic activity of GPCR-AAB in the absence (a) and presence of a related receptor blocker (f) as well as of monomeric Fab fragments (b), monomeric Fab fragments cross-linked by anti-Fab-antibodies (c), monomeric Fab fragments coupled to polyhistidine tag (d) and Fab fragments coupled to polyhistidine tag cross-linked by polyhistidine antibodies