Multiple Cell Surface Receptors for the Short Arms of Laminin: Integrin and RGD-dependent Proteins Mediate Cell Attachment only to Domains III in Murine Tumor Laminin

Cell surface molecules that interact with the cross formed by the three short arms of murine tumor laminin were studied using thermal perturbation, antibody and peptide blocking, and affinity chromatography. Several potential receptors for the laminin short arms were revealed that differed from those mediating cell attachment to the E8 (long ann) fragment. Two cell lines, Rugli and L8 attached well to E1-X (short arm) fragments of laminin. This attachment was blocked by antibodies against o~1 integrin chains. Other cells were unable to attach strongly to El-X, but attached to P1. This attachment was unaffected by antiBt integrin antibodies, but specifically blocked by the peptide GRGDS. By contrast, binding of Rugli cells was RGD independent and blocked by anti-Bt integrin antibodies. G7 and C2C12 myoblasts were very sensitive to GRGDS (IDm ~ 2 txg.ml -t) for attachment to P1 which implied that a non-/St series integrin, possibly tXvB3, was involved. On heat denaturation of P13 attachment remained sensitive to RGDS and IDso was unchanged. On heat denaturation of El-X, attachment remained sensitive to RGDS but the IDso increased to