Table 1. The major proteins identified in mouse mammary tissue ECM that were preserved in TMS.
The proteins were grouped according to their similarities in a family or their functions within ECM and were listed from high to low spectrum counts. FACIT, fibril-associated collagens with interrupted triple helices.
| # | Protein | Gene |
Accession number |
Protein molecular mass (kDa) |
Spectrum count |
Functions | |
| Collagen | 1 | Collagen type I alpha 1 chain |
Col1a1 | P11087 | 138 | 899 | Strengthens tissue structure; participates in ECM organization; interacts with metal ions and other proteins; regulates cell mobility |
| 2 | Collagen type III alpha 1 chain |
Col3a1 | P08121 | 139 | 812 | Strengthens tissue structure; associates with and facilitates collagen I fibrillogenesis; participates in ECM organization; interacts with metal ions and other proteins; regulates cell mobility |
|
| 3 | Collagen type I alpha 2 chain |
Col1a2 | Q01149 | 130 | 769 | Strengthens tissue structure; participates in ECM organization; interacts with metal ions and other proteins; regulates cell mobility |
|
| 4 | Collagen type V alpha 2 chain |
Col5a2 | Q3U962 | 145 | 143 | Mediates the assembly of other collagen fibrils; participates in ECM organization; interacts with metal ions and other proteins |
|
| 5 | Collagen type VI alpha 3 chain |
Col6a3 | E9PWQ3 | 354 | 123 | A major structural component of microfibrils; links BMs to nearby cells; participates in ECM organization; interacts with other proteins |
|
| 6 | Collagen type II alpha 1 chain |
Col2a1 | P28481 | 142 | 62 | Adds structure and strength to connective tissues that resist compression; participates in ECM organization; interacts with metal ions and other proteins |
|
| 7 | Collagen type V alpha 1 chain |
Col5a1 | O88207 | 184 | 60 | Participates in heterotypic assembly with other collagen fibrils and organization of ECM; interacts with metal ions and other proteins; regulates cell mobility |
|
| 8 | Collagen type VII alpha 1 chain |
Col7a1 | Q63870 | 295 | 56 | A major component of anchoring fibrils that contributes to epithelial BM organization and adherence by interacting with other ECM proteins; participates in ECM organization; regulates cell mobility |
|
| 9 | Collagen type IV alpha 2 chain |
Col4a2 | P08122 | 167 | 47 | A major structural component of BM that forms a meshwork together with laminins, proteoglycans, and nidogen/ entactin; participates in ECM organization; regulates cell adhesion; its cleaved product canstatin inhibits angiogenesis and tumor growth |
|
| 10 | Collagen type V alpha 3 chain |
Col5a3 | Q9JLI2 | 172 | 33 | Participates in heterotypic assembly with other collagen fibrils and organization of ECM; interacts with metal ions and other proteins; regulates cell mobility |
|
| 11 | Collagen type IV alpha 1 chain |
Col4a1 | P02463 | 161 | 27 | A major structural component of BM that forms a meshwork together with laminins, proteoglycans, and nidogen/ entactin; participates in ECM organization; regulates cell adhesion; its cleaved product arresten inhibits angiogenesis and tumor growth |
|
| 12 | Collagen type VI alpha 1 chain |
Col6a1 | Q04857 | 108 | 20 | A major structural component of microfibrils; links BM to nearby cells; participates in ECM organization; interacts with other proteins |
|
| 13 | Collagen type VI alpha 2 chain |
Col6a2 | Q02788 | 110 | 15 | A major structural component of microfibrils; links BM to nearby cells; participates in ECM organization; interacts with other proteins |
|
| 14 | Collagen type XI alpha 2 chain |
Col11a2 | Q64739 | 172 | 7 | Mediates the spacing and width of type II collagen; its proteolytic product poly(ADP-ribose) polymerase is involved in cellular stress response; interacts with calcium and metal ions |
|
| 15 | Collagen type XVI alpha 1 chain |
Col16a1 | A3KFV7 | 122 | 4 | Maintains the integrity of ECM; regulates cell attachment and integrin-mediated cell spreading and morphology changes |
|
| 16 | Collagen type XIV alpha 1 chain |
Col14a1 | B7ZNH7(+2) | 193 | 2 | Interacts with the interstitial collagen fibrils via type I collagen and mediates fibrillogenesis; plays an adhesive role by integrating collagen bundles; participates in ECM organization; regulates cell adhesion |
|
| 17 | Collagen type XXII alpha 1 chain |
Col22a1 | E9Q7P1 | 160 | 2 | A member of the FACIT subgroup of the collagen family; specifically localizes to tissue junctions; acts as a cell adhesion ligand |
|
| 18 | Collagen type XV alpha 1 chain |
Col15a1 | A2AJY2 | 138 | 1 | A member of the FACIT collagen family; its BM expression adheres the BM to the underlying connective tissue stroma; its cleaved product restin inhibits angiogenesis |
|
| 19 | Collagen type IV alpha 3 chain |
Col4a3 | Q9QZS0 | 162 | 1 | A major structural component of BM that forms a meshwork together with laminins, proteoglycans, and nidogen/ entactin; its cleaved fragment tumstatin has antiangiogenic and antitumor activities; participates in ECM organization; regulates cell adhesion |
|
| 20 | Collagen type IV alpha 5 chain |
Col4a5 | Q63ZW6 | 162 | 1 | A major structural component of BM that forms a meshwork together with laminins, proteoglycans, and nidogen/ entactin; participates in ECM organization; regulates cell adhesion |
|
| Glycoprotein and proteoglycan/ GAG |
21 | Periostin | Postn | Q62009 | 93 | 66 | Functions in tissue development and regeneration; binds to integrins to support adhesion and migration of epithelial cells; plays a role in cancer stem cell maintenance and metastasis |
| 22 | Laminin subunit gamma 1 |
Lamc1 | F8VQJ3 | 177 | 26 | The major noncollagenous constituent of BM; regulates cell adhesion, differentiation, migration, signaling, neurite outgrowth, and cancer metastasis; interacts with other ECM components; participates in ECM organization |
|
| 23 | Laminin subunit beta 1 |
Lamb1 | E9QN70(+1) | 202 | 13 | The major noncollagenous constituent of BM; regulates cell adhesion, differentiation, migration, signaling, neurite outgrowth, and cancer metastasis; interacts with other ECM components; participates in ECM organization |
|
| 24 | Laminin subunit alpha 1 |
Lama1 | P19137 | 338 | 9 | The major noncollagenous constituent of BM; regulates cell adhesion, differentiation, migration, signaling, neurite outgrowth, and cancer metastasis; interacts with other ECM components; participates in ECM organization |
|
| 25 | Laminin subunit beta 2 |
Lamb2 | Q61292 | 197 | 8 | The major noncollagenous constituent of BM; regulates cell adhesion, differentiation, migration, signaling, neurite outgrowth, and cancer metastasis; interacts with other ECM components; participates in ECM organization |
|
| 26 | Laminin subunit alpha 5 |
Lama5 | Q61001 | 404 | 5 | The major noncollagenous constituent of BM; regulates cell adhesion, differentiation, migration, signaling, neurite outgrowth, and cancer metastasis; interacts with other ECM components; participates in ECM organization |
|
| 27 | Fibronectin | Fn1 | P11276 | 273 | 23 | Binds cell surface and collagen, fibrin, heparin, DNA, and actin; regulates type I collagen deposition, cell morphology, adhesion, migration, and opsonization; mediates angiogenesis and tumor metastasis; its cleaved product anastellin binds fibronectin and induces fibril formation |
|
| 28 | Fibrillin 1 | Fbn1 | A2AQ53 | 312 | 16 | Fibrillin is secreted into ECM by fibroblasts and incorporated into the insoluble microfibrils, which appear to provide a scaffold for deposition of elastin |
|
| 29 | Fibrinogen alpha chain |
Fga | E9PV24(+1) | 87 | 14 | Forms fibrinogen with fibrinogen beta and gamma chains; thrombin converts fibrinogen to fibrin, which mediates blood clotting; various cleaved products of fibrinogen and fibrin regulate cell adhesion and spreading, display vasoconstrictor and chemotactic activities, and act as mitogens |
|
| 30 | Fibrinogen gamma chain |
Fgg | Q8VCM7 | 49 | 13 | Forms fibrinogen with fibrinogen alpha and beta chains; thrombin converts fibrinogen to fibrin, which mediates blood clotting; various cleaved products of fibrinogen and fibrin regulate cell adhesion and spreading, display vasoconstrictor and chemotactic activities, and act as mitogens |
|
| 31 | Fibrinogen beta chain |
Fgb | Q8K0E8 | 55 | 9 | Forms fibrinogen with fibrinogen alpha and gamma chains; thrombin converts fibrinogen to fibrin, which mediates blood clotting; various cleaved products of fibrinogen and fibrin regulate cell adhesion and spreading, display vasoconstrictor and chemotactic activities, and act as mitogens |
|
| 32 | Nidogen 1/ entactin |
Nid1 | P10493 | 137 | 9 | Essential component of BM; connects the networks formed by collagens and laminins to each other; plays a role in cell-ECM interactions |
|
| 33 | Tenascin-X | Tnxb | O35452 | 435 | 2 | The tenascins have antiadhesive effects, as opposed to fibronectin, which is adhesive; it is thought to function in matrix maturation |
|
| 34 | EMILIN 1 | Emilin1 | Q99K41 | 108 | 1 | Associates with elastic fibers at the interface between elastin and microfibrils; may play a role in the development of elastic tissues including large blood vessels, dermis, heart, and lung |
|
| 35 | Perlecan | Hspg2 | E9PZ16 | 470 | 30 | BM-specific; serves as an attachment substrate for cells; plays essential roles in vascularization; its cleaved products (endorepellin and LG3) have antiangiogenic and antitumor properties; binds to calcium and metal ions; maintains the integrity of BM |
|
| 36 | Lumican | Lum | P51885 | 38 | 13 | A proteoglycan class II member of the small leucine-rich proteoglycan family; binds to other extracellular components and mediates collagen fibril organization; ubiquitously distributed in most mesenchymal tissues; regulates epithelial cell migration and tissue repair |
|
| Other ECM proteins |
37 | Titin | Ttn | A2ASS6 | 3906 | 9 | Essential component of sarcomeres in striated muscles; provides structural support, flexibility, and stability to cell structures; mediates chemical signaling; serves as connections between microfilaments; contributes to the fine balance of forces between the two halves of sarcomere |
| 38 | Perilipin 1 | Plin1 | Q8CGN5 | 56 | 5 | Coats lipid storage droplets in adipocytes, thereby protecting them until they can be broken down by hormone-sensitive lipase; phosphorylation of perilipin is essential for the mobilization of fats in adipose tissues |
|
| 39 | Perilipin 4 | Plin4 | O88492 | 139 | 3 | Highly expressed in white adipose tissues, with lower expression in heart, skeletal muscle, and brown adipose tissues; coats lipid droplets in adipocytes to protect them from lipases |
|
| 40 | Elastin | Eln | P54320 | 72 | 3 | The major component of elastic fibers for structural support of tissues; participates in ECM organization; allows tissues to resume their shape after stretching or contracting; a major contributor to tissue stiffness |
|
| 41 | Dermatopontin | Dpt | Q9QZZ6 | 24 | 3 | A proteoglycan-binding cell adhesion protein that potentially functions in cell-matrix interactions through integrins; may enhance TGFB1 activity, inhibit cell proliferation, accelerate collagen fibril formation, and stabilize collagen fibrils against low-temperature dissociation |