Fibulin-4 and-5 are extracellular glycoproteins with essential non-compensatory roles in
elastic fiber assembly. We have determined how they interact with tropoelastin, lysyl
oxidase, and fibrillin-1, thereby revealing how they differentially regulate assembly. Strong
binding between fibulin-4 and lysyl oxidase enhanced the interaction of fibulin-4 with
tropoelastin, forming ternary complexes that may direct elastin cross-linking. In contrast,
fibulin-5 did not bind lysyl oxidase strongly but bound tropoelastin in terminal and central …