Fibulins: multiple roles in matrix structures and tissue functions.

The fibulins are a family of secreted glycoproteins associated with basement membranes, elastic fibers, and other matrices. They are expressed in a variety of tissues. Association with these matrix structures is mediated by their ability to interact with many extracellular matrix constituents. The seven members of the family are defined by the presence of two structural modules, a tandem repeat of epidermal growth factor-like modules and a unique C-terminal fibulin-type module. They act not only as intermolecular bridges within the extracellular matrix to form supramolecular structures, but also as mediators for cellular processes and tissue remodeling. These important functions of fibulins in a wide range of biological processes have been shown in in vitro systems, gene knockout mice, and human genetic disorders. In this review, we describe the structure and function of these proteins and discuss the implication of fibulins in development and diseases.