Incorporated into fibronectin-containing matrix fibers. May play a role in cell adhesion and migration along protein fibers within the extracellular matrix (ECM). Could be important for certain developmental processes and contribute to the supramolecular organization of ECM architecture, in particular to those of basement membranes. Homomultimerizes and interacts with various extracellular matrix components such as FN1, LAMA1, LMA2, NID, ACAN, CSPG2 and type IV collagen. Binding analysis demonstrated for isoform C a 100-fold stronger binding to the basement membrane protein NID than for isoform D. Interacts with FBLN7. Interacts with CCN3 (By similarity). Detected in most organs (brain, heart, lung, spleen, liver and kidney). Neurons are the predominant source of production in the brain. Not expressed significantly by astrocytes or microglia. The differential expression of the fibulin family contributes to the formation of molecularly distinct extracellular matrices already during early developmental stages of a large number of tissues. Increased expression at neonate stage in the brain. Expressed in interdigital regions of the handplate of a 12 dpc embryo and in the lateral perichondrial region. Similar expression persists in the 13 dpc handplate particularly in the perichondrial regions and apical aspects of the developing digits. Glucocorticoids suppressed mRNA expression and protein synthesis. Belongs to the fibulin family.