Phosphatase Family LMWPTP

Phosphatase Classification: Fold CC2 Superfamily CC2: Family LMWPTP

Low Molecular Weight Protein Tyrosine Phosphatase (LMWPTP) is a small protein (LMW) which dephosphorylates proteins on phospho-tyrosine. Most eukaryotic LMWPTP consist almost entirely of a phosphatase domain. The family has a single subfamily LMWPTP.

Evolution

LMWPTP is present in most eukaryotes, though lost from from alveolates, trypanosoma, leishmania. It is also found in many bacteria and archaea. It is usually a single copy per genome.

Domain

LMWPTP has a single domain: phosphatase domain.

Catalytic activity and functions

In eukaryotes, LMWPTP dephosphorylates many receptor tyrosine kinases, such PDGFR, InsR, and Eph [1]. It is a substrate for Src and Src phosphorylation creates a Grb2 SH2 domain-binding site. Accordingly it has been implicated in cancer progression [2]. Polymorphisms have also been implicated in metabolic and immune diseases. Human LMWPTP is also known to be a declycating agent, removing ribulose 5-phosphate from proteins [3, 4], in collaboration with Fructosamine Kinase. Yeast lacks classical TKs but the least homolog (LTP1) is a tyrosine-specific phosphatase and may dephosphorylate the immunophilin Fpr3 in vivo [5], on a residue likely phosphorylated by CK2 [6].

In prokaryotes, the molecular function is not fully understood. It is involved in the syntheisis and translocation of exopolysaccharides (EPS) and capsular polysaccharides (CPS) in E. coli. YwlE also acts as an arginine phosphatase [7]. In many species, the LMWPTP is chromosomally adjacent to a fructosamine kinase, suggesting that it's major role is in protein deglycation [8]. E. coli Wzb is known to dephosphorylate the atypical tyrosine kinase Wzc [9]. YwlE from B. subtilis and CG31469 from Drosophila are LMWPTPs that have been shown to have arginine phosphatase activity [10, 11].

References

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