CD49a ITGA1 (integrin α1), VLA-1α chain (very late antigen α1 chain), α-1 integrin chain
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
Type 1 glycoprotein
Monocyte
Muscle, Smooth
B Lymphocyte
NK Cell
T Cell
Megakaryocyte
Endothelium
Fibroblast
Mesenchymal Cell
Neural Cell
Hepatocyte
Melanoma Cell
200 / 200
210 / 210

Expression
CD49a is expressed on monocytes, megakaryocytes, activated T cells, cultured neuronal cells, melanoma cells, mesenchymal cells, smooth muscle cells, fibroblasts, hepatocytes, microvascular endothelium and at low levels on resting T cells.  Its expression on T cells is increased upon prolonged stimulation in vitro.  It is also found at increased levels on T lymphocytes in synovial joints of patients with rheumatoid arthritis and on melanoma cells. However, its expression is reduced following phytohemagglutinin stimulation.  CD49a expression on NK cells is upregulated by IL-2.

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

CD49a is a single-pass type-1 1152 aa glycoprotein.  It contains a 28 aa signal peptide, a large 206 aa N-terminal extracellular domain which contains an I-domain and 26 potential glycosylation sites, a transmembrane domain and a short 15 aa C-terminal cytoplasmic domain.  All integrin α chains have a conserved sequence found in the cytoplasmic domain immediately following the transmembrane domain (FYWS)-(RK)-x-G-F-F-x-R that may be the motif involved in heterodimer formation.  It noncovalently associated with the CD29 molecule to form the VLA-1 (a1/β1) integrin subunit. 

MOLECULAR MASS
Cell Type Unreduced Reduced
200 kDa 210 kDa

POST-TRANSCRIPTIONAL MODIFICATION: No information.

POST-TRANSLATIONAL MODIFICATION: No information.



Ligands
LIGANDS AND MOLECULES ASSOCIATED WITH CD49a

CD49a/CD29 binds laminin-1 and type-5 collagen through different binding sites.

Function
CD49a is an cell-cell adhesion molecule.  CD49a acts as an adhesion receptor for collagen IV and laminin-1.  The integrin CD49a/CD29 on choriocarcinoma and melanoma cells binds collagen and the E1 fragment of laminin.  CD49a is involved in leukocyte migration into tissues.  However, collagen binding is not mediated by CD49a/CD29 on cultured T lymphocytes.  In vitro studies have shown enhancement of effector T cell proliferation and cytokine production when bound to collagen via CD49a.  In vivo CD49a modulates effector inflammatory responses.  An inserted von Willebrand factor type 1 domain is thought to be involved in collagen binding.

BIOCHEMICAL ACTIVITY: No information.

DISEASE RELEVANCE AND FUNCTION OF CD49a IN INTACT ANIMAL

CD49 is involved in embryo development.  CD40a plays a role in inflammatory responses and fibrosis.

Comments
MOLECULAR INTERACTIONS-
PROTEIN AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD49a: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD49a: No information.


Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene 3672P56199
RatA35854P18614X52140
Antibodies

Revised June 25, 2008


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