CD148 PTPRJ (protein tyrosine phosphatase, receptor type J), DEP-1 (high density-enhanced PTP 1), HPTP-η
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
Type 1 glycoprotein
Hematopoietic Cell
Granulocyte
Monocyte
T Cell
Dendritic Cell
Platelet
Fibroblast
Nerve Cell
Kupffer Cell
200 / 200
250 / 250

Expression
CD148 is expressed among hematopoietic cells.  Expression is strong on monocytes, granulocytes (mainly at sites of inflammation) and dendritic cells.  Resting T cells express low levels but expression is upregulated following T-cell activation and CD45R0-psoitive express higher levels than naive cells.  Memory T-cells show higher levels of expression.  Platelets, fibroblasts, nerve cells, and Kupffer cells are also expressed.  It is a widely distributed antigen.



Structure
MOLECULAR FAMILY NAME:  Belongs to the protein tyrosine phosphatase family.

CD148 is a single-chain, type-1 1337 aa glycoprotein.  It is contains a 970 aa extracellular domain which contains 10 fibronectin III motifs, 34 potential N-linked glycosylation sites as well as O-glycosylation sites, a 25 aa transmembrane domain and a 342 aa intracellular cytoplasmic C-terminal domain which contains 1 protein tyrosine phosphatase domain.

MOLECULAR MASS
Cell type Unreduced Reduced Comment
PBMC 240-260 kDa 240-260 kDa Variation depending on investigator
HL60 200-250 kDa 200-250 kDa Variation depending on investigator and clone

POST-TRANSCRIPTIONAL MODIFICATION

Modification is unknown but possible.

POST-TRANSLATIONAL MODIFICATION

There are 34 potential N-glycosylation sites.  CD148 is O-glycosylated, sialydated, and is treated with endoglycosidase F.  O-glycanase and neuraminidase reduces the molecular weight but phosphorylation is unknown.

Ligands
LIGANDS AND MOLECULES ASSOCIATED WITH CD148

A natural ligand is unknown.



Function
CD148, a member of the protein tyrosine phosphatase (PTP) family, is known as a signaling molecules that regulate a variety of cellular processes including cell growth, differentiation, mitotic cycle and oncogenic transformation.  CD148 is present in all hematopietic lineages and was shown to negatively regulate T cell receptor signaling possibly through interfering with phosophorylation.  The levels of expression of CD148 increase on contact between epithelial cell lines suggesting a role in contact inhibition of cell growth.  The role of CD148 in the immune system is unclear but engagement with the antibody leads to cytokine secretion.  CD148 may have a role in arresting cell growth at confluence.

BIOCHEMICAL ACTIVITY

CD148 is a tyrosine phosphatase RPTPase, type 3.

DISEASE RELEVANCE AND FUNCTION OF CD148 IN INTACT ANIMAL

Defects in CD148 are found in cancers of the colon, lung and breast.

Comments
MOLECULAR INTERACTIONS -
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD148: No information.

SUBSTRATES

CD148 contains tyrosine phosphorylated proteins.

ENZYMES WHICH MODIFY CD148: No information.

ADDITIONAL INSIGHTS

Strong upregulation in fibroblast cultures grown to high density, could suggest that CD148 HPTP-eta/Dep-1 is involved in contact inhibition of cell growth.

Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene 5795Q12913
MouseD45212
Antibodies

Revised June 25, 2008


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