The first 3, N-terminal IgSF domains of human Lutheran bind human laminin 10/11.

(A) Cartoons depicting the structures of full-length Lu-Fc, Lu deletion mutants lacking one or more IgSF domains also expressed as Fc fusion proteins, and the structural analogue MUC18-Fc. (B) These constructs were captured on the anti-Fc biosensor cuvette, then purified human laminin 10/11 (final concentration 10 nM) was added at time 0 minute and association was recorded. Lu-Fc and the mutants Del 5 and Del 4-5 gave a positive binding curve, whereas the mutants Del 3-5 and Del 2-5 and the MUC18-Fc (MUC18) control failed to bind laminin 10/11. (C) Fluorescently labeled K562 transfectants expressing full-length Lu gp or domain deleted Lu gp were tested for adhesion in microplates coated with 10⁻¹² mole purified human laminin 10/11 per well. The extracellular IgSF domain organization of the Lu gp constructs expressed by these transfectants is the same as that depicted for the Fc fusion protein constructs in panel A.22 Transfectants expressing full-length Lu (FL) and mutants Del 5 and Del 4-5 adhered to laminin 10/11 coated plastic, whereas transfectants expressing mutants Del 3-5 or Del 2-5 did not adhere. Negative controls were a K562 transfectant expressing the blood group active LW glycoprotein tested as above (LW) and the K562 transfectant expressing full length Lu gp applied to immobilized bovine albumin (FL BSA).