CD257 TNFSF13b (tumor necrosis factor ligand superfamily member 13b), BLyS (B lymphocyte stimulator), BAFF, TALL1
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
Type 2 glycoprotein
Myeloid Cell
Dendritic Cell
Macrophage
Spleen
Lymph Node
Bone Marrow
T Cell
Monocyte
B Lymphocyte
Leukocyte
Peripheral blood
31 / 31

Expression
CD257 is expressed on dendritic cells, activated monocytes, B lymphocytes, macrophages, and myeloid cells.  Expression is in peripheral blood leukocytes, spleen, lymph node, bone marrow and T cells.  Lower expression is seen in non-lymphoid tissues such as placenta, heart, lung, and in fetal liver, thymus and pancreas.  Serum soluble CD257 is elevated in patients with autoimmune inflammatory conditions and in multiple myeloma and expression is found to be upregulated by IFN-γ.

Structure

MOLECULAR FAMILY NAME: Belongs to the tumor necrosis factor lsuperfamily.

CD257 is a single-pass type-2 glycoprotein.  It contains a 218 aa long extracellular domain which contains 2 N-glycoslation sites, a 21 aa hydrophobic transmembrane-spanning domain and an 152 aa N-terminal cytoplasmic domain.  The extracellular domain is shed as a result proteolysis in the extracellular stalk region shares homology with that of other TNF family members, particularly CD256.   

MOLECULAR MASS

POST-TRANSCRIPTIONAL MODIFICATION

Alternative splicing yields 3 different isoforms.

POST-TRANSLATIONAL MODIFICATION

CD257 is N-glycosylated.



Ligands
LIGANDS AND MOLECULE ASSOCIATED WITH CD257

CD257 binds to CD269, CD267 and CD268.

Function
The protein encoded by CD257 is a cytokine belonging to the TNF ligand family.  This cytokine is a ligand for receptors CD267 (TNFRSF13B/TACI), CD269 (TNFRSF17/BCMA), and CD268 (TNFRSF13C/BAFFR).  This cytokine is expressed in B cell lineage cells and acts in B cell survival, activation and differentiation of death of B cells.  It is involved in the growth factor and costimulator of Ig production.  There is resistance to apoptosis on some B cell tumors including CLL.  A biologic response is observed only among B cells due to their expression of the specific receptor.  CD257 is also involved as a costimulator in T-B cell interactions. 

BIOCHEMICAL ACTIVITY: No information.

DISEASE RELEVANCE AND FUNCTION OF CD257 IN INTACT ANIMAL

The critical role of CD257 in B-cell survival and activation, including its role in B-cell tumor survival, has made it a target for therapeutic applications.  Soluble CD257 retains the ability to activate cells, unlike many TNF family members, which are active only in membrane-expressed form.


Comments
MOLECULAR INTERACTIONS-
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD257: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD257: No information.

ADDITIONAL INSIGHTS

For further information see Moore, P. A. et al (1999) Science 285: 260-263.


Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene10673Q9Y275
Antibodies

Revised June 25, 2008


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