FnIII10

FnIII10 refers to the tenth fibronectin type III (FnIII) domain in the extracellular matrix protein fibronectin. Fibronectin is a large dimeric glycoprotein that mediates cell adhesion, migration, and extracellular matrix assembly. The FnIII modules are independently folding, approximately 90 amino acids in length, and they typically adopt a beta-sandwich fold without disulfide bonds.

FnIII10 is part of the type III region of fibronectin and contributes to integrin-mediated adhesion. The RGD motif, a short sequence critical for integrin binding, is located in FnIII10, whereas the adjacent FnIII9 carries a synergy sequence, PHSRN, that enhances binding to integrin receptors, particularly α5β1. The FnIII9–10 pair forms a functional unit whose surface-exposed loops engage receptors or co-receptors during cell attachment.

Functionally, FnIII10 participates in extracellular matrix interactions by presenting the RGD motif to cell surface receptors, facilitating adhesion and signaling. The domain is conserved across vertebrates and is studied as part of the fibronectin type III repeat array. Structural analyses, including X-ray and NMR studies, have shown that FnIII10 adopts the characteristic immunoglobulin-like beta-sandwich fold, with surface loops that position the RGD motif for receptor recognition.

FnIII10 is one of several FnIII domains arranged in succession within fibronectin, and its precise sequence and loop architecture can vary among species. It is a common target in studies of cell-ECM adhesion, protein folding of FnIII domains, and receptor interaction.