PTPRJ (protein tyrosine phosphatase, receptor type, J)

Multiple transcript variants encoding different isoforms have been found for this gene. Three transcripts are described in Ensembl (ID: ENSG149177). The first (ENST418331) represents the longer isoform and encodes a protein that consists of an extracellular fibronectin type 3 domain and a cytosolic catalytic domain. The second isoform (ENST440289) has multiple differences in the presence and absence of exons at its 3' end, compared to the first isoform. These differences produce a unique 3' UTR and the encoded protein is shorter and consists of the extracellular fibronectin type 3 domain without the cytosolic catalytic region. The third transcript (ENST278456) has the same length as the first, but it encodes a truncated protein, that consists of fibronectin type 3 domains. Only the first two isoforms are members of the human CCDS set and have been described in NCBI (IDs: NM_001098503.1, NM_001098503.1). The cDNA encoding PTPRJ/DEP-1 was isolated from a HeLa cell library (Ostman et al., 1994). The expression level and the activity of DEP-1 increase with cell density. This increase occurs gradually with increasing cell contact and is initiated before saturation cell density is reached. These observations suggest that DEP-1 may contribute to the mechanism of contact inhibition of cell growth.