Fibulin
Data - Fibulin 1
Mol mass: 71.5 kDa
Mol weight (Human Isoform A): 61 593 Residues: 566
Mol weight (Human Isoform B): 65 485 Residues: 601
Mol weight (Human Isoform C): 74 475 Residues: 683
Mol weight (Human Isoform D): 77 274 Residues: 703
Isolation: Argraves et al (1990) Kluge et al (1990)
Chromosome location: 22q13.3
Swiss Protein Database A B C D OMIM Knockout PUBMED
Data - Fibulin 2
Mol mass: 175 kDa
Mol weight (Human): 126 543 Residues: 1184
Chromosome location: 3p24-25
Swiss Protein Database OMIM Knockout
Data - Fibulin 3
Mol mass: 57 kDa
Mol weight (Human): 52765 Residues: 487
Chromosome location: 2p16
Swiss Protein Database OMIM Knockout
Data - Fibulin 4
Mol mass: 54 kDa
Mol weight (Human): 46534 Residues: 443
Chromosome location: 11q13
Swiss Protein Database OMIM Knockout
Data - Fibulin 5
Mol mass: 66 kDa
Mol weight (Human): - Residues: 448
Chromosome location:14q32.1
Swiss Protein Database OMIM Knockout

Fibulins are rod-like extracellular matrix molecules. The fibulins belong to the same superfamily as the Fibrillins and the Latent TGFbeta Binding Proteins. There are presently 5 known genes in the fibulin family.
Fibulin Structure
The 5 known fibulins all have a carboxyterminal FBLC motif that forms a globular domain (III). The FBLC motif is preceded by a rod-like domain (II). The length of domain II varies between different fibulins, reflecting the number of calcium-binding EGF repeats present. An aminoterminal globular domain (I) composed of anaphylatoxin-like motifs is found in fibulin-1 and -2. Fibulin-2 also contains a unique aminoterminal extended domain (N). Fibulin-1 is subject to alternative splicing of domain III, giving 4 different variant proteins (fibulin 1A-D).
Fibulin Interactions
Fibulin-2 forms disulfide-bond linked dimers, and fibulin-1 can form non-covalent dimers. Fibulin-1 interacts with nidogen, laminins, fibrillin, tropoelastin, fibronectin and fibrinogen. Fibulin-2 also binds nidogen, fibrillin, tropoelastin and fibronectin. In addition, collagen IV and perlecan interact with fibulin-2. Both fibulin-1 and -2 bind versican and aggrecan. The proteoglycan C-type lectin-like repeat in their G3 domain binds to calcium-binding EGF repeats in domain II of the fibulins. We believe that the dimeric fibulins act as cross-linkers, between proteoglycan/hyaluronan complexes. This may be pivotal in organizing the forming extracellular matrix in development and in response to damage. Nothing is yet known of oligomerization or interactions of fibulins 3-5.
Fibulin in Disease
No fibulin gene knock-out has yet been published. A mutation in fibulin-3 (EFEMP1) has been shown to segregate with the autosomal domainant eye diseases Malattia Leventinese and Doyne honeycomb retinal dystrophy [Stone et al., 1999]. Fibulin-5 (EVEC, DANCE) is upregulated in developing blood vessels, and in response to vascular injury such as atherosclerosis and angioplastic restenosis [Kowal et al., 1999; Nakamura et al., 1999].