Phosphatase Subfamily ACP2

Phosphatase Classification: Fold HP: Superfamily HP (histidine phosphatase): Family HP, branch 2: Subfamily ACP2

ACP2 is a phosphatase subfamily that usually has multiple copies per genome. Human has three copies with different tissue specificity. It is found in holozoa, ameobozoa, and some protists.

Evolution

ACP2 is found in holozoa, amoebozoa and some protists, but is absent from some fungi and most plants. There are usually multiple copies per genome. For example, human, fruit fly, C elegans have 3, 5 and 21 copies, respectively.

Domain

ACP2 has either transmembrane region or signal peptide cleavage site at N terminus. Some members have predicted C-terminal transmembrane regions, which may contain targeting sequence. For example, the membrane-proximal 12 residues of the human ACP2 tail are necessary and sufficient to mediate recycling and that the tyrosine motif of ACP2 (YRHV) is the critical sequence element mediating recycling [1].

Posttranslational modification

Human ACPP, prostatic acid phosphatase, is glycosylated at three asparagine residues (N62, N188, N301) and has potent antinociceptive effects when administered to mice [2].

Functions

Human ACPP (acid phosphatase, prostate) is a prostate epithelium-specific differentiation antigen (see GTEx), and is decreased in prostate carcinomas. It has been show to downregulate prostate cell growth by dephosphorylating phosphotyrosine on c-ErbB-2, an oncoprotein in prostate cells [3, 4]. His-12 and Asp-258 of ACPP, but not Cys-183 or Cys-281, are required for the phosphatase activity [5]. Though ACPP is supposed to be prostate specific, one of its isoforms is found in a broad of tissues [6].

Human ACPT (acid phosphatase, testicular) can act as a tyrosine phosphatase to modulate signals mediated by ErbB4 that are important for neuronal development and synaptic plasticity. ACPT and ErbB4 are both expressed in the brain where they are enriched at post-synaptic sites. ACPT can inhibit basal and neuregulin-induced tyrosine phosphorylation of ErbB4. ACPT-dependent dephosphorylation can regulate the proteolytic cleavage of ErbB4, and this process can be reversed by applying the tyrosine phosphatase inhibitor, pervanadate [7]. It is worthy pointing out ACPT is specifically expressed in testis rather than brain (see [8] and GTEx).

References

1. Obermüller S, Kiecke C, von Figura K, and Höning S. The tyrosine motifs of Lamp 1 and LAP determine their direct and indirect targetting to lysosomes. J Cell Sci. 2002 Jan 1;115(Pt 1):185-94. DOI:10.1242/jcs.115.1.185 |
2. Hurt JK, Fitzpatrick BJ, Norris-Drouin J, and Zylka MJ. Secretion and N-linked glycosylation are required for prostatic acid phosphatase catalytic and antinociceptive activity. PLoS One. 2012;7(2):e32741. DOI:10.1371/journal.pone.0032741 |
3. Meng TC and Lin MF. Tyrosine phosphorylation of c-ErbB-2 is regulated by the cellular form of prostatic acid phosphatase in human prostate cancer cells. J Biol Chem. 1998 Aug 21;273(34):22096-104. DOI:10.1074/jbc.273.34.22096 |
4. Chuang TD, Chen SJ, Lin FF, Veeramani S, Kumar S, Batra SK, Tu Y, and Lin MF. Human prostatic acid phosphatase, an authentic tyrosine phosphatase, dephosphorylates ErbB-2 and regulates prostate cancer cell growth. J Biol Chem. 2010 Jul 30;285(31):23598-606. DOI:10.1074/jbc.M109.098301 |
5. Zhang XQ, Lee MS, Zelivianski S, and Lin MF. Characterization of a prostate-specific tyrosine phosphatase by mutagenesis and expression in human prostate cancer cells. J Biol Chem. 2001 Jan 26;276(4):2544-50. DOI:10.1074/jbc.M006661200 |
6. Quintero IB, Araujo CL, Pulkka AE, Wirkkala RS, Herrala AM, Eskelinen EL, Jokitalo E, Hellström PA, Tuominen HJ, Hirvikoski PP, and Vihko PT. Prostatic acid phosphatase is not a prostate specific target. Cancer Res. 2007 Jul 15;67(14):6549-54. DOI:10.1158/0008-5472.CAN-07-1651 |
7. Fleisig H, El-Din El-Husseini A, and Vincent SR. Regulation of ErbB4 phosphorylation and cleavage by a novel histidine acid phosphatase. Neuroscience. 2004;127(1):91-100. DOI:10.1016/j.neuroscience.2004.04.060 |
8. Yousef GM, Diamandis M, Jung K, and Diamandis EP. Molecular cloning of a novel human acid phosphatase gene (ACPT) that is highly expressed in the testis. Genomics. 2001 Jun 15;74(3):385-95. DOI:10.1006/geno.2001.6556 |