Fibrillin-1 and fibulin-2 interact and are colocalized in some tissues.

Microfibrils 10-12 nm in diameter are found in elastic and non-elastic tissues with fibrillin as a major component. Little is known about the supramolecular structure of these microfibrils and the protein interactions it is based on. To identify protein binding ligands of fibrillin-1, we tested binding of recombinant fibrillin-1 peptides ...
to different extracellular matrix proteins in solid phase assays. Among the proteins tested, only fibulin-2 showed significant binding to rF11, the N-terminal half of fibrillin-1, in a calcium-dependent manner. Surface plasmon resonance demonstrated high affinity binding with a Kd = 56 nM. With overlapping recombinant fibrillin-1 peptides, the binding site for fibulin-2 was narrowed down to the N terminus of fibrillin-1 (amino acid positions 45-450). Immunofluorescence in tissues demonstrated colocalization of fibrillin and fibulin-2 in skin, perichondrium, elastic intima of blood vessels, and kidney glomerulus. Fibulin-2 was not present in ocular ciliary zonules, tendon, and the connective tissue around kidney tubules and lung alveoli, which all contain fibrillin. Immunogold labeling of fibulin-2 on microfibrils in skin was found preferentially at the interface between microfibrils and the amorphous elastin core, suggesting that in vivo the interaction between fibrillin-1 and fibulin-2 is regulated by cellular expression and deposition as well as by protein-protein interactions.
Mesh Terms:
Amino Acid Sequence, Animals, Base Sequence, Calcium-Binding Proteins, Cattle, Child, DNA Primers, Extracellular Matrix Proteins, Humans, Kinetics, Male, Mice, Microfilament Proteins, Microscopy, Immunoelectron, Molecular Sequence Data, Protein Binding, Recombinant Proteins, Skin, Species Specificity
J. Biol. Chem.
Date: Aug. 09, 1996
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