CD29 ITGB1 (integrin β1 chain),  platelet GPIIa, VLA (CD49)-β chain
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
Type 1 glycoprotein
Leukocyte
Endothelial Cell
Neuroblastoma cell
Skin
Placenta
Fibroblast
Skeletal muscle
Lymphoma Cell
T Cell
Liver
Kidney
Platelet
Blood Cell
Astrocytoma cell
Hepatoma Cell
115 / 115
130 / 130

Expression
CD29 is expressed on most cells.  It is expressed on all leukocytes, although only at low levels on granulocytes.  On T cells, CD29 is expressed at higher levels on memory than naïve cells in some species including humans and mice.  Expression is not on red blood cells.  Four isoforms,  β1-A-D have varies expressions.  Isoform β1-A is widely expressed, isoform β1-B is expressed in skin, liver, skeletal muscle, placenta, vein endothelial cells, neuroblastoma cells, lymphoma cells, hepatoma cells and astrocytoma cells, isoform β1-C is expressed in muscle, kidney, liver, placenta, umbilical vein endothelial cells, fibroblasts, embryonal kidney cells, platelets and several blood cell lines, and isoform β1-D is specifically expressed in various muscles.

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

CD29 is a single-pass type-1 glycoprotein.  It contains an extracellular domain, a transmembrane domain and a cytoplasmic domain.  It forms heterodimers with many integrin a subunits including the CD49a-f (a1-a 6), and CD51(aV), antigens and, in nonlymphoid tissues, a7-a9.  The CD49a-f/CD29 heterodimers are also termed the very late antigens (VLA-1 to VLA-6) because 2 of them, VLA-1 and -2, appear on lymphocytes several weeks after stimulation.  There are 4 CD29 isoforms, A-D, with different cytoplasmic domains which are generated by alternative splicing.  The B isoform, b1 3'v, is found in the placenta and is expressed on human umbilical vein endothelial cells (HUVECs) as well as lymphoma, neuroblastoma and hepatoma cell lines.  The C isoform, b1, is expressed on platelets and a number of hematopoietic cell lines but is not detected on peripheral blood lymphocytes or HUVECs.  The D isoform is exclusively expressed in skeletal and cardiac muscle.

MOLECULAR MASS
Cell Type Unreduced Reduced
115 kDa 130 kDa

POST-TRANSCRIPTIONAL MODIFICATION

Alternatively splicing yields 4 different isoforms. 

POST-TRANSLATIONAL MODIFICATION: No information.


Ligands
LIGANDS AND MOLECULES ASSOCIATED WITH CD29

Integrins which include CD29 bind to several cell surfaces and extracellular matrix molecules.  CD29 /CD49a complex binds type-4 collagen and laminin.  CD29/49b complex binds type-1 collagen.  CD29/CD49c complex binds fibronectin, laminin-V, laminin-1, entactin and collagen.  CD29/CD49d complex binds CD106 (VCAM-1), connecting segment-1 (CS-1 isoform of fibronectin), microbial ligand invasin and thrombospondin.  CD29/CD49e complex binds fibronectin and neural adhesion molecule L1.  CD29/CD49f complex binds laminin invasin and merosin.  CD29/CD51 complexes bind fibronectin and vitronectin.




Function
CD29 acts as a fibronectin receptor and has adhesion to ligands such as CD106 (VCAM-1) and MAdCAM-1 and adhesion to matrix proteins, collagen, laminin and fibronectin.  Integrin heterodimers containing CD29 mediate cell-cell and cell-matrix adhesion (see CD49a-f and CD51). The adhesive properties of CD29 heterodimers on T cells can be regulated by cell activation, possibly through interactions between the cytoplasmic domain of CD29 and the cytoskeleton.  The different cytoplasmic domains in the A-D isoforms may allow interactions with different intracellular elements.

BIOCHEMICAL ACTIVITY OF CD29: No information.

DISEASE RELEVANCE AND FUNCTION OF CD29 IN INTACT ANIMAL

CD29 is a critical molecule involved in cell adhesion and recognition in a variety processes including embryogenesis, hemostasis, tissue repair, immune response, metastatic diffusion of tumor cells and development.  It is essential to the differentiation of hematopoietic stem cells with tumor progression and matastasis/invasion.  Various studies implicated a role for CD29 in signaling pathways in HHV-8 entry into target cells, a role for integrins in peripheral lymphoid tissue compartmentalization and a role in the development of certain diseases such as Glanzmann thrombasthenia, severe brain malformations and chondrodysplasis.

Comments
MOLECULAR INTERACTIONS-
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD29: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD29: No information.


Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene 3688P05556
MousePL0104P09055X15202
MouseS01659Y00769
Antibodies
12G10   View Reactivity
3S3   View Reactivity
4B7   View Reactivity
FW4-101   View Reactivity
HUTS-21   View Reactivity
JB1B   View Reactivity
K20   View Reactivity
MAR4   View Reactivity

Revised June 25, 2008


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