CD53 MCR, OX-44 (rat), tetraspanin-25, Tspan-25
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
Type 3 glycoprotein, 4 span
T Cell
B Cell
Monocyte
Macrophage
Granulocyte
Dendritic Cell
Osteoblast
Osteoclast
Leukocyte
Thymocyte
32 / 32
42 / 42

Expression
CD53 is expressed by leukocytes, T and B cells, monocytes, macrophages, granulocytes, dendritic cells, osteoblasts and osteoclasts.  It is absent from platelets, erythrocytes, red blood cells, and nonhematopoietic cells.  In the rat and mouse, CD53 is expressed on only 12% of thymocytes and is largely absent from the CD4+CD8+ population.  CD53 expression on thymocytes is induced by T cell receptor engagement during repertoire selection.


Structure
MOLECULAR FAMILY NAME: Belongs to the tetraspanin family.

CD53 is a multi-pass type-3, 4 span 219 aa glycoprotein.  It contains 2 unequal extracellular loops which contain 2 N-glycosylation sites in the large loop, 4 putative transmembrane domains and short ends that are located in the cytoplasm.  CD53 is a member of the tetraspan superfamily, the tetraspan family signature sequence is found between transmembrane domains 2 and 3, G-x(3)-[LIVMF]-x(2)-[GSA]-[LIVMF](2)-G-C-x-[GA]-[STA]-x(2)-[EG]-x(2)-[CW]-[LIVM](2).  Epitope mapping of anti-rat CD53 mAbs has proved the major hydrophilic region to be extracellular, which is consistent with the proposed topology of TM4SF molecules.  Gene mapping data suggest that CD37 and CD53 have evolved by gene duplication and divergence from a common ancestral gene.

MOLECULAR MASS
Cell Type Unreduced Reduced Comment
Unspecified 32-42 kDa

POST-TRANSCRIPTIONAL MODIFICATION: No information.

POST-TRANSLATIONAL MODIFICATION

CD53 contains 2 N-glycosylation sites present in the large extracellular region. The Mr is dropped to about 25 kDa upon treatment with endoglycosidase F.

Ligands
Co-immunoprecipitation and flow cytometric energy transfer studies have shown that CD53 associates non-covalently with a number of other molecules. CD53 associates with CD2 in rat NK and T cells, the integrin CD29/CD49d VLA-4 in a human T cell line, MHC Class I and II, CD19, CD20, CD21, CD37, CD81 and CD82 in human B cells, and a protein tyrosine phosphatase in rat lymph node cells.  No extracellular ligand has been identified for CD53.

LIGANDS AND MOLECULES ASSOCIATED WITH CD53
Molecule Comment
Other tetraspans
VLA-4
HLA-DR


Tetraspans, integrins and MHC class II molecules may be in 1 large complex.  In the rat, CD53 is associated with CD2 and a tyrosine phosphatase activity.




Function
CD53 mediates signal transduction events that play a role in the regulation of cell development, activation, growth and mortality.  CD53 is a cell surface glycoprotein that is know to complex with integrins.  It contributes to the transduction of C2-generated signal in T and NK cells and has been suggested to play a role in growth regulation.  Crosslinking CD53 induces calcium mobilization, signal transduction and oxidative burst formation in monocytes and promotes activation of human B cells and granulocytes and in rat macrophages, NK cells and T cells.  Decreased expression is found in activated and migrating leukocytes.  CD53 associates with other tetraspan molecules, VLA-4 and HLA-DR, and may form part of a large complex of integrins, tetraspans and MHC class II molecules.  In rat, CD53 is associated with CD2 and signal transduction via tyrosine phosphatase activity.

BIOCHEMICAL ACTIVITY: No information.

DISEASE RELEVANCE AND FUNCTION OF CD53 IN INTACT ANIMAL

Familial deficiency of CD53 has been linked to an immunodeficiency associated with recurrent infectious disease caused by bacteria, fungi and viruses.


Comments

MOLECULAR INTERACTIONS -
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD53: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD53: No information.



Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene 963P19397
MouseX97227
RatA39574P24485M57276
Antibodies
HI29   View Reactivity

Revised June 25, 2008


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