CD49c ITGA3 (integrin α3-chain), VLA-3α chain
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
Type 1 glycoprotein
Adhesion cell
30 / 30
125 / 125
150 / 150

Expression
CD49c is expressed on most adhesion cell lines and at low levels on monocytes, and B and T lymphocytes.  It is expressed on most cultured adherent cell lines but not on lymphoid cell lines.

Structure
MOLECULAR FAMILY NAME: Belongs to the integrin a chain family.

CD49c is a single-pass type-1 1019 aa glycoprotein.  It contains a large N-terminal extracellular domain which contains 7-fold repeat structures with putative cation-binding motif in 3 of 4 C-termimal repeats which remain disulfide-linked and 14 potential N-glycoslation sites, a 28 aa transmembrane domain and a short 32 aa cytoplasmic domain containing 2 spliced isoforms, α and β isoforms.  CD49c is proteolytically cleaved into two disulfide linked fragments of 125 kDa and 30 kDa.  All integrin α-chains have a conserved sequence found in the cytoplasmic domain immediately following the transmembrane domain (FYWS)-(RK)-xG-F-F-x-R, which may be the motif involved in heterodimer formation.  CD49c is an a3 integrin subunit which associates with the CD29 molecule to form the VLA-2 (α3/b1) integrin subunit.  It belongs to the integrin a subclass which does not contain an I-domain.
 
MOLECULAR MASS
Cell Type Unreduced Reduced
150 kDa 125 kDa, 30 kDa

POST-TRANSCRIPTIONAL MODIFICATION:

Alternative splicing yields 2 different isoforms.  The isoforms known as A and B differ only in cytoplasmic domain.

POST-TRANSLATIONAL MODIFICATION

CD49c undergoes post-translational cleavage in the extracellular domain to yield disulfide-linked light and heavy chains that join with β1 to form an integrin that interacts with many extracellular-matric proteins.

Ligands
LIGANDS AND MOLECULES ASSOCIATED WITH CD49c

The integrin CD49c/CD29 has been shown to bind many ligands, but its affinity for these ligands depends on the cell type on which it is expressed, the divalent cation concentrations, and the presence of other integrin heterodimers on the cell.  Thus, CD49c/CD29 binds fibronectin at the RGD sites but this binding is only detectable on cells that do not express the CD49e/CD29 integrin.  CD49c/CD29 also binds collagen, laminin-1, laminin-5 and entactin, but this binding is not inhibited by the RGD-containing peptides.  CD49c/CD29 has been shown to mediate the binding of cells to epiligrin, an extracellular matrix protein on epithelial basement membranes.

Function
CD49c associates with the TM4 family of proteins and CD29 to form VLA2, an adhesion receptor for extracellular matrix components and may be involved in signal transduction.  It acts as a receptor for collagen, laminin-5 and fibronectin.  K562 cells, which do not express any endogenous CD49 antigens, failed to bind fibronectin, collagen or laminin-5 when transfected with CD49c cDNA. They showed binding to epiligrin, suggesting a role for CD49c/CD29 in mediating signal transduction and cell adhesion to the epithelial basement membranes.  CD49c/CD29 has been found at contact sites between cultured cells and so may have a role in cell-cell as well as cell-matrix adhesion.

BIOCHEMICAL ACTIVITY: No information.

DISEASE RELEVANCE AND FUNCTION OF CD49c IN INTACT ANIMAL

Knockout mice show prenatal lethality and kidney abnormalities.

Comments
MOLECULAR INTERACTIONS-
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD49c: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD49c: No information.


Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HamsterA35761P17852J05281
HumanEntrezgene 3675P26006
Antibodies
17C6   View Reactivity
C3II.1   View Reactivity

Revised June 25, 2008


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