PPEF/PP7 protein Ser/Thr phosphatases

Abstract

PPEF/PP7 represents one of the five subfamilies of the PPP protein Ser/Thr phosphatases. Studies published in recent years point to a role of plant PP7 at a crossroad of different pathways of light and stress signalling. In animals, PPEFs are highly expressed in sensory neurons, and Drosophila PPEF phosphatase, rdgC, is essential for dephosphorylation of rhodopsin. Expression profiling suggests that mammalian PPEF may play a role in stress-protective responses, cell survival, growth, proliferation, and oncogenesis. Despite structural similarities of the catalytic domains and the fact that some of these phosphatases are involved in light perception both in animals and in plants, the plant and non-plant representatives of this group have distinct domain architecture and appear not to be orthologues.

Fig. 1

Structural relationships between the catalytic domains of PPEF, PP7 and PP5 phosphatases from various eukaryotic lineages. Sequences start 5 AA residues before the conserved GDXHGQ motif and end 4 AA after the conserved SAPNY motif. Analysis was performed using Neighbor-Net [78]. Gap sites were excluded. The PPEF, plant PP7 and PP5 subfamilies are shaded in different colours, and their representative domain architectures are shown. Species are colour-coded as follows: red animals; green plants; blue various unicellular eukaryotes. The following groups are represented: animals (nematodes: Brugia malayi, Caenorhabditis elegans; arthropods: Drosophila melanogaster; chordates: Homo sapiens; cnidarians: Nematostella vectensis; echinoderms: Strongylocentrotus purpuratus), apicomplexans (Cryptosporidium parvum, Plasmodium falciparum); dinoflagellates (Karenia brevis); kinetoplastids (Trypanosoma brucei); microsporidians (Encephalitozoon cuniculi); oomycetes (Phytophthora infestans). Ostreococcus species, which have both PPEF and plant-type PP7 phosphatases, are shown in larger font and are colour shaded. X Isoforms predicted to be inactive or to have reduced activity. Accession numbers for each sequence are indicated