The three-dimensional structure of the tenth type III module of fibronectin: an insight into RGD-mediated interactions.

The solution structure of the tenth type III module of fibronectin has been determined using nuclear magnetic resonance techniques. The molecule has a fold similar to that of immunoglobulin domains, with seven beta strands forming two antiparallel beta sheets, which pack against each other. Both beta sheets contribute conserved hydrophobic residues to a compact core. The topology is more similar to that of domain 2 of CD4, PapD, and the extracellular domain of the human growth hormone receptor than to that of immunoglobulin C domains. The module contains an Arg-Gly-Asp sequence known to be involved in cell adhesion. This tripeptide is solvent exposed and lies on a conformationally mobile loop between strands F and G, consistent with its cell adhesion function.