Abstract
Human diploid fibroblasts (TIG-3) were shown to attach and spread onto substrata coated with collagen, fibronectin, laminin and vitronec-tin. The cell attachment to these proteins required divalent cations. Mg2+ stimulated the cell attachment to all the proteins, while Ca2+ alone was not effec-tive for the attachment to collagen and laminin. A mild trypsin treatment had prevented cells from attaching to the laminin, while it had no effect on the at-tachment to the other proteins. The fibronectin fragment, which retained cell binding activity, inhibited the cells from attaching and spreading onto fibronec-tin, but it did not cause any inhibition on the other proteins. The synthetic pep-tide GRGDSP inhibited the cells from attaching and spreading onto fibronectin and vitronectin, while it did not cause any inhibition on collagen and laminin. In attempts to isolate distinct receptors for these proteins, we were able to purify proteins very similar to the fibronectin and vitronectin receptors of human placenta. Based on the differential properties of the attachment of TIG-3 cells to these proteins and biochemical data, we indicate that human diploid fibroblasts have distinctive binding sites (receptors) for collagen, fibronectin, laminin and vitronectin.
