CD1e R2
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Lineage Restricted Molecule
Type 1 glycoprotein
Cortical Thymocyte
T Cell
Dendritic Cell
Leukocyte
B Cell
Langerhans Cell
Thymocyte
Cytokine
Monocyte
36 / 36

Expression
The CD1 family is expressed on leukocytes, dendritic cells, Langerhans cells, B cells and T cells in thymocyte differentiation and on activation.  Expression can be regulated by cytokines and activation stimuli.  CD1e is expressed on cortical thymocytes and with a less intensity on CD4+ and CD8+ thymocytes.  CD1 is absent on mature peripheral blood T cells but intracytoplasmic expression is detected on activated T lymphocytes.  The molecules are induced on monocytes by treatment with the granulocyte-macrophage colony stimulating factor (GM-CSF) alone or by GM-CSF plus IL-4.



Structure
MOLECULAR FAMILY NAME:  Belongs to the immunoglobulin supergene family.

CD1e is a single-pass type-1 a chain glycoprptein.  It contains an extraacellular domain which contains 3 domains, α1, α2 and α3 each 90 aa, 2 potential N-glycosylation sites in domains α1 and α2, a transmembrane domain and a short cytoplasmic domain containing a tyrosine-based motif YXXZ which essential for access to late endsomes and lipid binding.  It is non-covalently associated with b2 microglobulin and has a structural similarities to MHC class I molecules. 

MOLECULAR MASS
Cell Type Unreduced Reduced
Thymocytes 43 kDa-49 kDa

POST-TRANSCRIPTIONAL MODIFICATION

The alternative splicing pattern is tissue specific and gives rise to membrane attached and soluble forms.  Multiple splicing patterns have been found for all CD1 transcripts except for CD1b.  A complex 5 bands splicing pattern was described for CD1e on resting peripheral blood mononuclear cells (PBMC), myeloid cell lines KG1a, HEL, THP1 and HL60, B cell lines Daudi and Raji, and in the pre-T cell lines MOLT-4.  Phythohemagglutinin (PHA) activated PBMC which express only 1 high molecular transcript.

POST-TRANSLATIONAL MODIFICATION

Potential N-glycoslated sites are 2 on CD1e.

Ligands
LIGANDS AND MOLECULES ASSOCIATED WITH CD1e

Some T cells recognize an antigen in a CD1-restricted manner.  Mouse NK1+ T lymphocytes which have a restricted TCR repertoire recognize murine CD1, although there is conflicting data.  Antigens presented by human CD1b were identified as microbial lipids.  A recombinant form of the murine CD1 binds synthetic peptides with micromolar affinities.  It showed preference for longer peptides than seen for class I and resembles class II peptide binding.



Function
CD1e associates with β2 microglobulin and non-peptide Ag presentation.  CD1s have been demonstrated to restrict T-cell responses to non-peptide lipid and glycolipid antigens.  CD1 molecules could be involved in the delivery of signals for lymphocyte activation.  Some anti-CD1 mAbs produced inhibition of bacterial superantigen thymocytes proliferation.  On PBMC, depending on the epitope recognized by the mAb, an inhibitory or enhanced effect on the proliferative response to the phosphokinase C (PKC) activator phorbol myristate acetate (PMA) has been observed.  The expression of CD1 molecules on thymocytes has been related to a role in thymic T-cell development. NK1+ cells a subset of T cells found in high frequencies in the mature compartment of the mice thymus are involved in the development of NK cells.  These cells, found in high frequencies in bone marrow and liver, have CD1 molecules as their ligand. It has been postulated that through their NK-like activity, the liver is actively involved in the peripheral cell deletion of T cells arriving from the intestine through the portal vein.  By this mechanism, these cells may be involved in the induction of oral tolerance.  The CD1e function is unknown but it has a hypothelical role that may be to transport microbial lipids that accumulate in the Golgi and endoplasmic reticulum and transport them to other compartments for processing.  The molecules accumulate in the Golgi of immature dendritic cells, then they transfer to laet endosomes in mature dendritic cells where the molecules are cleaved and become soluble.

BIOCHEMICAL ACTIVITY: No information.

DISEASE RELEVANCE AND FUNCTION OF CD1e IN INTACT ANIMAL: No information.

Comments
CD1 genes, except CD1b, are transcribed in the same direction and all lack classical promoter elements.

MOLECULAR INTERACTIONS -
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD1e: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD1e: No information.

ADDITIONAL INSIGHTS

CD1e is homologous to histocompatibility antigens but is not genetically linked to the histocompatibility locus.

Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene 913P15812
Antibodies

Revised June 25, 2008


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