Fig. 1. Representations of the human ₁ and chicken ß₁ collagen IV receptor and the swapped integrin chimera. (A) HA1, or wild-type receptors, express full-length ₁ integrin. (B) SW1 receptors have the extracellular regions swapped onto their opposing transmembrane and cytoplasmic domains (Briesewitz et al., 1995). (C) SßX receptors are altered from the SW1 chimera by extension of the ß cytoplasmic domain by 10 residues. (D) Two constructs with 10-residue insertions (bold) were engineered: SßX-ßcyt, a duplication of the first 10 residues of the ß cytoplasmic domain (underlined); and SßX-X10, a random sequence predicted to be -helical.