Pseudophosphatases (obsolete)

Functions

• Receptor PTPs. Most receptor PTPs have two tandem phosphatase domains. The 2nd phosphatase domain has no or negligible activity. The 2nd domain can interact with 1st domain in both intra- and intermolecular manners [1].

Controversial pseudophosphatases

PTPRN (IA-2) and PTPRN2

Human PTPRN and PTPRN2 have been proposed to be enzymatically inactive due to mutations at catalytic Cx5R motif and WPD motif [2]. However, PTPRN2 has been reported to be phosphatidylinositol phosphatase [3].

PTPN23 (HD-PTP)

PTPN23 was reported to be catalytically inactive, - no phosphatase activity toward tyrosine or lipid. It was proposed that serine at position 1452 within Cx5R catalytic motif caused the inactivity. Replacing serine with alanine, which is found in catalytically active PTPs, can restore the phosphatase activity [4].

However, another study found SRC, E-cadherin, and beta-catenin are direct substrates of PTPN23 [5].

References

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