Fibronectin is a high-molecular weight glycoprotein of the extracellular matrix that binds to membrane-spanning receptor proteins called integrins. It is approved for marketing as a topical solution in India by Central Drugs Standard Control organization in 2020 under the brand name FIBREGA for chronic wounds. Fibronectin also binds to other extracellular matrix proteins such as collagen, fibrin, and heparan sulfate proteoglycans.
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 which the glycosaminoglycan is joined through a tetrasaccharide bridge. The Ser residue is generally in the sequence -Ser-Gly-X-Gly-, although not every protein with this sequence has an attached glycosaminoglycan. The chains are long, linear carbohydrate polymers that are negatively charged under physiological conditions due to the occurrence of sulfate and uronic acid groups. Proteoglycans occur in connective tissue.
Versican is a large extracellular matrix proteoglycan that is present in a variety of human tissues. It is encoded by the VCAN gene.
Perlecan (PLC) also known as basement membrane-specific heparan sulfate proteoglycan core protein (HSPG) or heparan sulfate proteoglycan 2 (HSPG2), is a protein that in humans is encoded by the HSPG2 gene. The HSPG2 gene codes for a 4,391 amino acid protein with a molecular weight of 468,829. It is one of the largest known proteins. The name perlecan comes from its appearance as a "string of pearls" in rotary shadowed images.
Heparan sulfate (HS) is a linear polysaccharide found in all animal tissues. It occurs as a proteoglycan in which two or three HS chains are attached in close proximity to cell surface or extracellular matrix proteins. In this form, HS binds to a variety of protein ligands, including Wnt, and regulates a wide range of biological activities, including developmental processes, angiogenesis, blood coagulation, abolishing detachment activity by GrB, and tumour metastasis. HS has also been shown to serve as cellular receptor for a number of viruses, including the respiratory syncytial virus. One study suggests that cellular heparan sulfate has a role in SARS-CoV-2 Infection, particularly when the virus attaches with ACE2.
Transforming growth factor beta 1 or TGF-β1 is a polypeptide member of the transforming growth factor beta superfamily of cytokines. It is a secreted protein that performs many cellular functions, including the control of cell growth, cell proliferation, cell differentiation, and apoptosis. In humans, TGF-β1 is encoded by the TGFB1 gene.
Biglycan is a small leucine-rich repeat proteoglycan (SLRP) which is found in a variety of extracellular matrix tissues, including bone, cartilage and tendon. In humans, biglycan is encoded by the BGN gene which is located on the X chromosome.
Transforming growth factor-beta 2 (TGF-β2) is a secreted protein known as a cytokine that performs many cellular functions and has a vital role during embryonic development. It is an extracellular glycosylated protein. It is known to suppress the effects of interleukin dependent T-cell tumors. There are two named isoforms of this protein, created by alternative splicing of the same gene.
Betaglycan also known as Transforming growth factor beta receptor III (TGFBR3), is a cell-surface chondroitin sulfate / heparan sulfate proteoglycan >300 kDa in molecular weight. Betaglycan binds to various members of the TGF-beta superfamily of ligands via its core protein, and bFGF via its heparan sulfate chains. TGFBR3 is the most widely expressed type of TGF-beta receptor. Its affinity towards all individual isoforms of TGF-beta is similarly high and therefore it plays an important role as a coreceptor mediating the binding of TGF-beta to its other receptors - specifically TGFBR2. The intrinsic kinase activity of this receptor has not yet been described. In regard of TGF-beta signalling it is generally considered a non-signaling receptor or a coreceptor. By binding to various member of the TGF-beta superfamily at the cell surface it acts as a reservoir of TGF-beta.
Syndecan 1 is a protein which in humans is encoded by the SDC1 gene. The protein is a transmembrane heparan sulfate proteoglycan and is a member of the syndecan proteoglycan family. The syndecan-1 protein functions as an integral membrane protein and participates in cell proliferation, cell migration and cell-matrix interactions via its receptor for extracellular matrix proteins. Syndecan-1 is a sponge for growth factors and chemokines, with binding largely via heparan sulfate chains. The syndecans mediate cell binding, cell signaling, and cytoskeletal organization and syndecan receptors are required for internalization of the HIV-1 tat protein.
FBLN1 is the gene encoding fibulin-1, an extracellular matrix and plasma protein.
Transforming growth factor beta-3 is a protein that in humans is encoded by the TGFB3 gene.
Integrin beta-6 is a protein that in humans is encoded by the ITGB6 gene. It is the β6 subunit of the integrin αvβ6. Integrins are αβ heterodimeric glycoproteins which span the cell’s membrane, integrating the outside and inside of the cell. Integrins bind to specific extracellular proteins in the extracellular matrix or on other cells and subsequently transduce signals intracellularly to affect cell behaviour. One α and one β subunit associate non-covalently to form 24 unique integrins found in mammals. While some β integrin subunits partner with multiple α subunits, β6 associates exclusively with the αv subunit. Thus, the function of ITGB6 is entirely associated with the integrin αvβ6.
Collagen alpha-6(IV) chain is a protein that in humans is encoded by the COL4A6 gene.
Serglycin, also known as hematopoietic proteoglycan core protein or secretory granule proteoglycan core protein, is a protein that in humans is encoded by the SRGN gene. It is primarily expressed in hematopoietic cells and endothelial cells, and is the only known intracellular proteoglycan.
Lumican, also known as LUM, is an extracellular matrix protein that, in humans, is encoded by the LUM gene on chromosome 12.
Collagen alpha-1(XIV) chain is a protein that in humans is encoded by the COL14A1 gene. It likely plays a role in collagen binding and cell-cell adhesion.
Fibromodulin is a protein that in humans is encoded by the FMOD gene.
Beta-1,4-galactosyltransferase 7 also known as galactosyltransferase I is an enzyme that in humans is encoded by the B4GALT7 gene. Galactosyltransferase I catalyzes the synthesis of the glycosaminoglycan-protein linkage in proteoglycans. Proteoglycans in turn are structural components of the extracellular matrix that is found between cells in connective tissues.
Dermatopontin also known as tyrosine-rich acidic matrix protein (TRAMP) is a protein that in humans is encoded by the DPT gene. Dermatopontin is a 22-kDa protein of the noncollagenous extracellular matrix (ECM) estimated to comprise 12 mg/kg of wet dermis weight. To date, homologues have been identified in five different mammals and 12 different invertebrates with multiple functions. In vertebrates, the primary function of dermatopontin is a structural component of the ECM, cell adhesion, modulation of TGF-β activity and cellular quiescence). It also has pathological involvement in heart attacks and decreased expression in leiomyoma and fibrosis. In invertebrate, dermatopontin homologue plays a role in hemagglutination, cell-cell aggregation, and expression during parasite infection.
