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.

#ProteinGeneAccession
number
Protein
molecular
mass (kDa)
Spectrum
count
Functions
Collagen1Collagen
type I
alpha 1 chain
Col1a1P11087138899Strengthens tissue structure; participates in ECM organization;
interacts with metal ions and other proteins; regulates cell
mobility
2Collagen
type III
alpha 1 chain
Col3a1P08121139812Strengthens tissue structure; associates with and facilitates
collagen I fibrillogenesis; participates in ECM organization;
interacts with metal ions and other proteins; regulates
cell mobility
3Collagen
type I alpha
2 chain
Col1a2Q01149130769Strengthens tissue structure; participates in ECM organization;
interacts with metal ions and other proteins; regulates
cell mobility
4Collagen
type V
alpha 2 chain
Col5a2Q3U962145143Mediates the assembly of other collagen fibrils; participates
in ECM organization; interacts with metal ions and other
proteins
5Collagen
type VI alpha
3 chain
Col6a3E9PWQ3354123A major structural component of microfibrils; links BMs to
nearby cells; participates in ECM organization; interacts with
other proteins
6Collagen
type II
alpha 1 chain
Col2a1P2848114262Adds structure and strength to connective tissues that resist
compression; participates in ECM organization; interacts
with metal ions and other proteins
7Collagen
type V
alpha 1 chain
Col5a1O8820718460Participates in heterotypic assembly with other collagen
fibrils and organization of ECM; interacts with metal ions
and other proteins; regulates cell mobility
8Collagen
type VII alpha
1 chain
Col7a1Q6387029556A 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
9Collagen
type IV
alpha 2 chain
Col4a2P0812216747A 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
10Collagen
type V
alpha 3 chain
Col5a3Q9JLI217233Participates in heterotypic assembly with other collagen fibrils
and organization of ECM; interacts with metal ions and other
proteins; regulates cell mobility
11Collagen
type IV
alpha 1 chain
Col4a1P0246316127A 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
12Collagen
type VI
alpha 1 chain
Col6a1Q0485710820A major structural component of microfibrils; links BM to
nearby cells; participates in ECM organization; interacts with
other proteins
13Collagen
type VI
alpha 2 chain
Col6a2Q0278811015A major structural component of microfibrils; links BM to
nearby cells; participates in ECM organization; interacts with
other proteins
14Collagen
type XI
alpha 2 chain
Col11a2Q647391727Mediates 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
15Collagen
type XVI
alpha 1 chain
Col16a1A3KFV71224Maintains the integrity of ECM; regulates cell attachment
and integrin-mediated cell spreading and morphology
changes
16Collagen
type XIV
alpha 1 chain
Col14a1B7ZNH7(+2)1932Interacts 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
17Collagen
type XXII
alpha 1 chain
Col22a1E9Q7P11602A member of the FACIT subgroup of the collagen family;
specifically localizes to tissue junctions; acts as a cell
adhesion ligand
18Collagen
type XV
alpha 1 chain
Col15a1A2AJY21381A member of the FACIT collagen family; its BM expression
adheres the BM to the underlying connective tissue
stroma; its cleaved product restin inhibits angiogenesis
19Collagen
type IV
alpha 3 chain
Col4a3Q9QZS01621A 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
20Collagen
type IV
alpha 5 chain
Col4a5Q63ZW61621A 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
21PeriostinPostnQ620099366Functions 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
22Laminin
subunit
gamma 1
Lamc1F8VQJ317726The 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
23Laminin
subunit
beta 1
Lamb1E9QN70(+1)20213The 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
24Laminin
subunit
alpha 1
Lama1P191373389The 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
25Laminin
subunit
beta 2
Lamb2Q612921978The 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
26Laminin
subunit
alpha 5
Lama5Q610014045The 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
27FibronectinFn1P1127627323Binds 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
28Fibrillin 1Fbn1A2AQ5331216Fibrillin is secreted into ECM by fibroblasts and incorporated
into the insoluble microfibrils, which appear to provide a
scaffold for deposition of elastin
29Fibrinogen
alpha chain
FgaE9PV24(+1)8714Forms 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
30Fibrinogen
gamma chain
FggQ8VCM74913Forms 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
31Fibrinogen beta
chain
FgbQ8K0E8559Forms 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
32Nidogen 1/
entactin
Nid1P104931379Essential component of BM; connects the networks formed
by collagens and laminins to each other; plays a role in
cell-ECM interactions
33Tenascin-XTnxbO354524352The tenascins have antiadhesive effects, as opposed to
fibronectin, which is adhesive; it is thought to function in
matrix maturation
34EMILIN 1Emilin1Q99K411081Associates 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
35PerlecanHspg2E9PZ1647030BM-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
36LumicanLumP518853813A 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
37TitinTtnA2ASS639069Essential 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
38Perilipin 1Plin1Q8CGN5565Coats 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
39Perilipin 4Plin4O884921393Highly 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
40ElastinElnP54320723The 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
41DermatopontinDptQ9QZZ6243A 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