Table 2.
Non-collagenous ECM proteins
| Protein | Location | Description | Refs |
|---|---|---|---|
| Agrin | Skeletal muscles | Large PG that is crucial in the development of the neuromuscular junction; contains laminin G domains, Kazal-type serine protease inhibitor domains and epidermal growth factor domains | 142–144 |
| Integrin-binding sialoprotein (also known as bone sialoprotein) | Bone | Phosphorylated and sulphated glycoprotein that is crucial for the structure of mineralized matrix; binds to calcium and hydroxyapatite and mediates cell attachment through an RGD sequence that recognizes the vitronectin receptor | 145–147 |
| Matrilins | Cartilage and connective tissues | Non-collagenous, disulphide-bonded proteins that are involved in the formation of filamentous networks; contains von Willebrand factor A domains | 148–151 |
| Elastin | Arteries, connective tissue, lungs, skin and bladder | One of two components of elastic fibres that provide structural integrity along with reversible extensibility and deformability; forms covalently crosslinked polymers | 152–155 |
| Fibrinogen | Blood | Soluble glycoprotein, which, after cleavage by thrombin, is converted to fibrin monomer molecules that self-associate to form insoluble, homopolymeric ‘clots’ | 153,156, 157 |
| Fibrillin | Connective tissues and cardiovascular tissues | Predominant component of microfibrils, which forms a sheath around elastin in the formation of elastic fibres | 158,159 |
| Fibulins | Basement membranes, blood and arteries | Calcium-binding glycoprotein that is found in fibrillar matrices and blood | 153,160, 161 |
| Netrins | Basement membranes | Laminin-related protein that is involved in axon guidance and the development of the vasculature, lung, pancreas, muscle and the mammary gland | 162,163 |
| SPARC (also known as osteonectin) | Bone | Cysteine-rich, acidic, calcium-binding glycoprotein that is required for collagen calcification, mineralization initiation and mineral crystal formation | 164,165 |
| Secreted phosphoprotein 1 (also known as osteopontin) | Bone and kidneys | Negatively-charged glycoprotein that is involved in the attachment of cells to mineralized bone matrix | 146,166, 167 |
| Reelin | Brain | Large glycoprotein that is involved in guiding neuron and glial cell positioning in the developing brain | 168,169 |
| Tenascins | Connective tissues | Glycoproteins that are involved in mediating inflammatory and fibrotic processes | 119,153, 170,171 |
| Vitronectin | Blood | Adhesive glycoprotein that is involved in blood coagulation and wound healing | 172,173 |
ECM, extracellular matrix; PG, proteoglycan.