PROTEIN-TYROSINE PHOSPHATASE, NONRECEPTOR-TYPE, 18; PTPN18

Alternative titles; symbols

• BRAIN-DERIVED PHOSPHATASE; BDP1

HGNC Approved Gene Symbol: PTPN18

Cytogenetic location: 2q21.1 Genomic coordinates (GRCh38): 2:130,356,011-130,375,404 (from NCBI)

▼ Cloning and Expression
Using a PCR amplification strategy, Kim et al. (1996) isolated nonreceptor protein-tyrosine phosphatase-18 (PTPN18), which they called brain-derived phosphatase (BDP1), from a human fetal brain cDNA library. The PTPN18 cDNA encodes a deduced 459-amino acid protein with no transmembrane domain and a calculated molecular weight of 50 kD. PTPN18 has a PEST motif and shares the greatest homology with members of the PTP-PEST gene family. When transiently expressed in 293 cells, PTPN18 hydrolyzed p-nitrophenylphosphate, confirming that it is a functional protein-tyrosine phosphatase. Northern blot analysis demonstrated that PTPN18 is expressed not only in brain but also in colon and several different tumor-derived cell lines. PTPN18 was found to differentially dephosphorylate autophosphorylated tyrosine kinases which are known to be overexpressed in tumor tissues.

▼ Mapping
The International Radiation Hybrid Mapping Consortium mapped the PTPN18 gene to chromosome 2 (stSG1724).