|CD103||ITGAE (integrin αE chain), HML-1 antigen (human mucosal lymphocyte antigen 1)|
|Molecule Type||Antigen Expression||Molecular Weight|
Min / Max
|Non-lineage Restricted Molecule|
Type 1 glycoprotein
|25 / 25|
150 / 150
|CD103 is expressed on more than 90% of intestinal intraepithelial lymphocytes (IEL), on about 40% of lamina propria T lymphocytes in the intestine, and on the majority of intraepithelial lymphocytes present in extraintestinal sites such as bronchi, inflammatory skin/breast/salivary glands and tumoral epitheliums. CD103 is present on 1-2% of circulating T cells but is absent from most cells in secondary lymphoid tissue. There is expression on 0.5-5% lymphocytes in peripheral blood and peripheral lymphoid organs. CD103 mRNA is found in the thymus and spleen as well as tissues such as lung, small intestine, and colon, which contain large populations of intraepithelial lymphocytes. It is expressed in the prostate and ovary and in tissues such as the pancreas and testis, where b7 mRNA transcripts are not detectable. There is also expression on the enteropathy-associated T cell lymphomas, hairy B cell leukemia and on adult T cell leukemias associated with HTLV-1. There is activation and TGF-b-1 induced CD103 expression.|
|MOLECULAR FAMILY NAME: Belongs to the integrin a chain family.|
CD103 is a single-pass type-1 1160 aa glycoprotein. It contains an extracellular domain which contains 7 repeats characteristic of integrin α chains including 3 potential EF-Hand cation-binding motifs, a 193 aa transmembrane domain which contains an integrin inserted domain (I- domain), a 55 aa extra domain (X-domain) found in the N-terminal to the I-domain and contains a proteolytic cleavage site which contains the intrachain cleavage site and a continuous stretch of 18 charged residues, 16 of which are acidic. CD103 also contains a 30 aa intracytoplasmic domains containing a GFKKR (gly-phe-phe-lys-arg) motif involved in ligand-induced conformation changes in integrins. CD103 is the integrin aE subunit, E for epithelial-associated, which usually forms a heterodimer with the integrin b7 subunit. It belongs to the subgroup of integrin a subunits with an I-domain. Unlike the other members of this group, it is cleaved into 2 chains, an N-terminal chain of 25 kDa and a C-terminal chain of 150 kDa, which remain linked by disulfide bonds.
POST-TRANSCRIPTIONAL MODIFICATION: No information.
The mature protein is post-translationally cleaved into the heavy fragment of about 1000 aa and the light fragment of about 150 aa. These components remain associated by disulfide bridge.
|The integrin aEβ7 binds E-cadherin.|
LIGANDS AND MOLECULES ASSOCIATED WITH CD103
|CD103 associates with integrin β7 to form the human mucosal lymphocyte antigen and the complex binds to E-cadherin which is a component of epithelial cell membranes. Stimulation of PBL with PHA induces CD103 expression. This interaction may be important in the homing, retention and activation of CD103-expressing lymphocytes in the intestinal epithelium. CD103 is involved in tissue-specific retention of lymphocytes at the basolateral surface of intestinal epithelial cells and possible has an accessory function for the activation of intraepithelial lymphocytes (IELs). In vitro experiments using antibody suggest that CD103 is able to submit an activation signal, particularly in IELs. Knockout mice have reduced numbers of IELs, but this is strain-dependent, suggesting a redundancy in the major function of CD103.|
BIOCHEMICAL ACTIVITY: No information.
DISEASE RELEVANCE AND FUNCTION OF CD103 IN INTACT ANIMAL
The contribution of CD103 to the localization of IEL has been examined in integrin b7 deficient mice. CD103 is a marker or IELs and for lymphomas deriving from IELs but must be interpreted conservatively because CD103 can be induced on non-IELs by TGFβ.
|MOLECULAR INTERACTIONS -|
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD103: No information.
SUBSTRATES: No information.
ENZYMES WHICH MODIFY CD103: No information.
CD103 is an useful marker for intraepithelial lymphocytes on either normal or and tumor cells. Yet caution should be taken as overinterpretation of its expression as evidence for the intraepithelial origin of positive cells since its expression can be induced by activation and/or by TGFb1. The murine orthologue of aE is defined by M290 antibody and the probable rat orthlologue defined by RGL-1, RGL-2 and RGL 3 antibodies and the probable chicken orthologue.
Database accession numbers
Revised June 25, 2008