Cross-linking of fibrinogen and fibrin by tTG. Comparison of FXIIIa (A) and guinea pig tTG-cross-linked products (B). Lanes 1 and 4: normal recombinant fibrin; lanes 2 and 5: γQ398N/Q399N/K406R; lanes 3 and 6: γK406R. Bands are labeled as in Figure 1. With the exception of a faint γ-dimer band, the cross-linking pattern in tTG-cross-linked normal recombinant fibrin is similar to that of FXIIIa- and tTG-cross-linked γK406R. Nature of the cross-linking bands was identified by Western blotting.