Fibulin (FY-beau-lin) (now known as Fibulin-1

FBLN1 FBLN1 is the gene encoding fibulin-1, an extracellular matrix and plasma protein. Function Fibulin-1 is a secreted glycoprotein that is found in association with extracellular matrix structures including fibronectin-containing fibers, elastin-co ...

) is the prototypic member of a multigene family, currently with seven members. Fibulin-1 is a

calcium-binding glycoprotein Calcium-binding proteins are proteins that participate in calcium signaling, calcium cell signalling pathways by binding to Ca2+, the calcium ion that plays an important role in many cellular processes. Calcium-binding proteins have specific domains ...

. In

vertebrates Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...

fibulin-1 FBLN1 is the gene encoding fibulin-1, an extracellular matrix and plasma protein. Function Fibulin-1 is a secreted glycoprotein that is found in association with extracellular matrix structures including fibronectin-containing fibers, elastin- ...

is found in

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the c ...

and

extracellular matrices In biology, the extracellular matrix (ECM), also called intercellular matrix, is a three-dimensional network consisting of extracellular macromolecules and minerals, such as collagen, enzymes, glycoproteins and hydroxyapatite that provide structu ...

. In the extracellular matrix, fibulin-1 associates with

basement membrane The basement membrane is a thin, pliable sheet-like type of extracellular matrix that provides cell and tissue support and acts as a platform for complex signalling. The basement membrane sits between Epithelium, epithelial tissues including mesot ...

s and

elastic fiber Elastic fibers (or yellow fibers) are an essential component of the extracellular matrix composed of bundles of proteins (elastin) which are produced by a number of different cell types including fibroblasts, endothelial, smooth muscle, and air ...

s. The association with these matrix structures is mediated by its ability to interact with numerous extracellular matrix constituents including

fibronectin Fibronectin is a high- molecular weight (~500-~600 kDa) glycoprotein of the extracellular matrix that binds to membrane-spanning receptor proteins called integrins. Fibronectin also binds to other extracellular matrix proteins such as collage ...

proteoglycan Proteoglycans are proteins that are heavily glycosylated. The basic proteoglycan unit consists of a "core protein" with one or more covalently attached glycosaminoglycan (GAG) chain(s). The point of attachment is a serine (Ser) residue to whic ...

laminin Laminins are a family of glycoproteins of the extracellular matrix of all animals. They are major components of the basal lamina (one of the layers of the basement membrane), the protein network foundation for most cells and organs. The laminins ...

s and

tropoelastin Elastin is a protein that in humans is encoded by the ''ELN'' gene. Elastin is a key component of the extracellular matrix in gnathostomes (jawed vertebrates). It is highly elastic and present in connective tissue allowing many tissues in the bo ...

. In blood, fibulin-1 binds to

fibrinogen Fibrinogen (factor I) is a glycoprotein complex, produced in the liver, that circulates in the blood of all vertebrates. During tissue and vascular injury, it is converted enzymatically by thrombin to fibrin and then to a fibrin-based blood clo ...

and incorporates into clots. Fibulins are secreted glycoproteins that become incorporated into a fibrillar extracellular matrix when expressed by cultured cells or added exogenously to cell monolayers. The five known members of the family share an elongated structure and many calcium-binding sites, owing to the presence of tandem arrays of epidermal growth factor-like domains. They have overlapping binding sites for several basement-membrane proteins, tropoelastin, fibrillin, fibronectin and proteoglycans, and they participate in diverse supramolecular structures. The amino-terminal domain I of fibulin consists of three

anaphylatoxin Anaphylatoxins, or complement peptides, are fragments ( C3a, C4a and C5a) that are produced as part of the activation of the complement system. Complement components C3, C4 and C5 are large glycoproteins that have important functions in the imm ...

-like (AT) modules, each approximately 40 residues long and containing four or six cysteines. The structure of an AT module was determined for the complement-derived anaphylatoxin C3a, and was found to be a compact alpha-helical fold that is stabilized by three disulphide bridges in the pattern Cys14, Cys25 and Cys36 (where Cys is cysteine). The bulk of the remaining portion of the fibulin molecule is a series of nine EGF-like repeats.

Genes

FBLN2 Fibulin-2 is a protein that in humans is encoded by the ''FBLN2'' gene. This gene encodes an extracellular matrix protein, which belongs to the fibulin family. This protein binds various extracellular ligands and calcium. It may play a role during ...

FBLN3 EGF-containing fibulin-like extracellular matrix protein 1 is a protein that in humans is encoded by the ''EFEMP1'' gene. Gene This gene encodes a member of the fibulin family of extracellular matrix glycoproteins. Like all members of this fam ...

FBLN4 EGF-containing fibulin-like extracellular matrix protein 2 is a protein that in humans is encoded by the ''EFEMP2'' gene. A large number of extracellular matrix proteins have been found to contain variations of the epidermal growth factor (EGF) do ...

FBLN5 Fibulin-5 (also known as DANCE (developmental arteries and neural crest epidermal growth factor (EGF)-like)) is a protein that in humans is encoded by the ''FBLN5'' gene. Function The protein encoded by this gene is a secreted, extracellular m ...

, FBLN7 and

HMCN1 Hemicentin-1 is a protein that in humans is encoded by the ''HMCN1'' gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' o ...

is also known as "fibulin-6".

References

External links

* * Protein domains Blood proteins {{biochemistry-stub