More recently, fibrillin-3 was described and is believed to be located mainly in the brain. Along with the brain, fibrillin 1 has been localized in the gonads and ovaries of field mice.

Fibrillins, such as FBN3, are extracellular matrix macromolecules that perform architectural functions in most connective tissues. Fibrillins assemble into microfibrils that can be identified ultrastructurally as uniform, small-diameter fibrils.By sequencing clones obtained from a size-fractionated fetal brain cDNA library, Nagase et al. cloned FBN3, which they also called KIAA1776. The deduced 2,816-amino acid protein has an N-terminal signal sequence, numerous EGF-like repeats, and several 8-cysteine modules called TB domains. FBN3 shares more than 60% amino acid identity with FBN1, FBN2, and mouse Fbn2.