Non-receptor protein phosphatase (NRPTP), also known as cytoplasmic PTPs, belongs to the classical PTP with non-transmembrane structure. The phosphatase catalytic activity is control by the regulatory sequence flanking the catalytic domain through interaction at the active site that modulates activity or controls substrate specificity. In addition, the regulatory sequences also control the subcellular distribution (1). NRPTP family is involved in varieties of cellular processes. For example, PTPN14 plays an important role in regulating lymphatic function and choanal development in human (2). PTPN20 is targeted to sites of actin polymerization in response of varied extracellular stimuli (3). PTPN11 participates in the signal transduction from the cell surface to nucleus and acts as downstream receptor (4).

Reference
1. Tonks, N.K. (2006) Protein tyrosine phosphatases: from genes, to function, to disease. Nat Rev Mol Cell Biol, 7, 833-846 PMID: 17057753
2. Au, A.C., Hernandez, P.A., Lieber, E., Nadroo, A.M., Shen, Y.M., Kelley, K.A., Gelb, B.D. and Diaz, G.A. (2010) Protein tyrosine phosphatase PTPN14 is a regulator of lymphatic function and choanal development in humans. Am J Hum Genet, 87, 436-444. PMID: 20826270
3. Fodero-Tavoletti, M.T., Hardy, M.P., Cornell, B., Katsis, F., Sadek, C.M., Mitchell, C.A., Kemp, B.E. and Tiganis, T. (2005) Protein tyrosine phosphatase hPTPN20a is targeted to sites of actin polymerization. Biochem J, 389, 343-354. PMID: 15790311
4. Jakob, S., Schroeder, P., Lukosz, M., Buchner, N., Spyridopoulos, I., Altschmied, J. and Haendeler, J. (2008) Nuclear protein tyrosine phosphatase Shp-2 is one important negative regulator of nuclear export of telomerase reverse transcriptase. J Biol Chem, 283, 33155-33161. PMID: 18829466

    RPTP belongs to the Classical Protein Tyrosine Phosphatase (classical PTP). RPTP, also known as receptor protein tyrosine phosphatase, is defined by its extracellular domains, which functions as upstream signal receptor. Some phosphatases contain large extracellular domain while others contain small extracellular domain. RPTP members function its phosphatase activity utilizing its cytoplasmic domains. Most members contain two phosphatase domains, named D1(membrane proximal) and D2. D1 domain is responsible for 99% of catalytic activity, while the second phosphatase domain D2 appears to bind multiple downstream partners. Although D2 is inactive, it can be converted to a catalytic active domain by change two amino acids (KNRLVN and WPEQGVP) (1). RPTP family is involved in varieties of cellular processes. DLAR, DPTP10D and DPTP99A phosphatase are highly expressed in the growth cones of motor neuron axons, suggesting the RPTP plays an important role in axon guidance. CDC45 is expressed exclusively in the haematopoietic system and involved in TCR cell signaling. RPTPalpha is highly expressed in the developing brain of various species, especially expressed in glia, suggesting that RPTPalpha is involved in controlling neuronal migration (2).

Reference
1. Johnson, K.G. and Van Vactor, D. (2003) Receptor protein tyrosine phosphatases in nervous system development. Physiol Rev, 83, 1-24. PMID: 12506125.
2. den Hertog, J., Blanchetot, C., Buist, A., Overvoorde, J., van der Sar, A. and Tertoolen, L.G. (1999) Receptor protein-tyrosine phosphatase signalling in development. Int J Dev Biol, 43, 723-733. PMID: 10668981