Elastin fibers are predominantly composed of the secreted monomer tropoelastin. This protein assembly confers elasticity to all vertebrate elastic tissues including arteries, lung, skin, vocal folds, and elastic cartilage. In this study we examined the mechanism of cell interactions with recombinant human tropoelastin. Cell adhesion to human tropoelastin was divalent cation-dependent, and the inhibitory anti-integrin ␣ V ␤ 3 antibody LM609 inhibited cell spreading on tropoelastin, identifying integrin ␣ V ␤ 3 as the major fibroblast cell surface receptor for human tropoelastin. Cell adhesion was unaffected by lactose and heparin sulfate, indicating that the elastin-binding protein and cell surface glycosaminoglycans are not involved. The C-terminal GRKRK motif of tropoelastin can bind to cells in a divalent cation-dependent manner, identifying this as an integrin binding motif required for cell adhesion.

Background: Cellular integrin ␣ V ␤ 3 binds to RKRK at the C-terminal tail of tropoelastin. Results: Inhibition of integrin ␣ V ␤ 5 hinders cell adhesion to tropoelastin constructs comprising domains 17 and 18. Conclusion: Integrin ␣ V ␤ 5 mediates cell adhesion to tropoelastin through a central region. Significance: Understanding the cell adhesion activity of tropoelastin gives improved insight into the physiological and pathological cell responses to this protein.

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