Phosphatase Subfamily PTC7

Phosphatase Classification: Fold PPM (PP2C): Superfamily PPM (PP2C): Family PPM (PP2C): Subfamily PTC7

Evolution

The PTC7 subfamily is found throughout eukaryotes. It is single copy in most opisthokonts.

Domain Architecture

PTC7 proteins typically consist of a single structural domain: a PPM-fold phosphatase domain. A PLAT domain is found N-terminal of the phosphatase domain in Monosiga, some algae and scattered other organisms, and Monosiga also encodes an uncertain C-terminal LIM domain.

Functions

Yeast Ptc7p, dephosphorylates and activates the mitochondrial hydroxylase Coq7p (Cat5p) and so activates coenzyme Q6 biosynthesis. Ptc7 may reverse the action of the Coq8 kinase (ABC1/YGL119W) (see, e.g. [1]). COQ7 is found in most eukaryotes, except plants and excavates [2]. COQ7 in humans is targeted to mitochondria, cleaved to become trapped in these organelles, and then function in the biosynthesis of ubiquinone, a cofactor in the electron transport chain. The uncleaved form of these proteins in the nucleus [3].

Subcellular localization

Human PPTC7 is reported as a mitochondrial protein by multiple datasets summarized in Mitominer, and knockdown in human cells has an effect on mitochondrial respiration [4], though PPTC lacks a mitochondria targeting signal TargetP 1.1. Because COQ7 is localized in both mitochondria and nucleus, further studies need to clarify whether PTC7 is localized to nucleus and dephosphorylates COQ7 in nucleus.

References

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Technical notes

Accessory PLAT domain is found in a small number of single cellular eukaryotes

The combination of PLAT and PPM domain is found in sparsely, by BLASTing monosiga PTC7, both full sequence and the region containing PLAT and PPM, against eukaryotes NR dataset. domain (1-400). Below are the organisms and their genes that have the domain combination of PLAT and PPM:

• Green algae: Monoraphidium neglectum (KIY99478.1)
• Eudicots: Capsella rubella (XP_006283668.1)
• Algae (cryptomonads): Guillardia theta (XP_005819750.1)
• Fungus: Blastocystis hominis (CBK25361.2)
• Algae: Micromonas sp. RCC299 (XP_002499745.1)

Algae: Bathycoccus prasinos (XP_007509274.1)