Phosphatase Subfamily PGP

Phosphatase Classification: Fold HAD: Superfamily HAD: Family NagD: Subfamily PGP

PGP is ubiquitous in eukaryotes and has been reported to act on both proteins and small molecules.

Evolution

PGP is found in most eukaryotes, typically in a single copy. Vertebrates encode two members: PGP and PDXP.

Domain

PGPs have a single HAD-fold domain. C. elegans PGP (K02D10.1) has at least three alternative splicing isoforms. One of the isoforms, supported by spliced ESTs, has a NIPSNAP domain at C-terminal (another two isoforms encode solely HAD and NIPSNAP domain, respectively).

Functions

PDXP (Chronophin) is abundantly expressed in brain [1] (see also GTEx RNA-seq data). PDXP has two distinct substrates.

• Pyridoxal 5'-phosphate. PDXP was first identified as pyridoxal phosphatase, which catalyzes the dephosphorylation of pyridoxal 5'-phosphate (PLP) and pyridoxine 5'-phosphate. PLP is the active form of vitamin B6 that acts as a coenzyme in maintaining biochemical homeostasis [1, 2, 3] and an important biomarker measures B6 status [4].

• Cofilin. PDXP dephosphorylates cofilin at serine, regulating assembly and disassembly of actin filaments [5, 6, 7]. slingshot, also dephosphorylates cofilin.

In contrast with PDXP, PGP (AUM) is widely expressed in different tissues (see also GTEx RNA-seq data). PGP is a putative tyrosine-specific phosphatase [8], but its physiological substrates are unknown. It also has a conserved phosphoglycolate phosphatase activity.

The yeast PGP, PHO13, has serine phosphatase activity against histone II-A and casein [9], and also acts on the synthetic small-molecule substrate PNPP (para-nitrophenyl phosphate). Deletion of PHO13 increases expression of pentose phosphate pathway genes and allows more efficient use of xylose.

References

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