The IG3 repeat in domain IV of perlecan is the principal site of interaction with nidogens, binding to the G2 domain (Mayer et al. 1998, Hopf et al. 2001). Domain V of perlecan also binds to nidogen (Brown et al. 1997). Nidogen-1 in turn binds to the laminin gamma1-subunit (Mayer et al. 1998), providing a bridge between the two proteins (Hopf et al. 1999, 2001, Kvansakul et al. 2001).