View source for Phosphatase Subfamily FIG4

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[[Phosphatase classification|Phosphatase Classification]]: [[Phosphatase_Fold_CC1|Fold CC1]]: [[Phosphatase_Superfamily_CC1|Superfamily CC1]]:  [[Phosphatase_Family_Sac|Family Sac]]: [[Phosphatase_Subfamily_FIG4|Subfamily FIG4]] (SAC3)

=== Evolution ===
The FIG4 (SAC3) subfamily is conserved in eukaryotes. It is present in almost all the 203 eukaryotic genomes in [http://resdev.gene.com/gOrtholog/view/cluster/MC0000617/overview gOrtholog database (internal)].

=== Domain ===
The FIG4 (SAC3) subfamily has a single structural domain, SAC phosphatase domain. 

=== Function ===
FIG4 is a phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P2)  phosphatase. It functions in the complex with PIKfyve (the sole kinase for PtdIns(3,5)P2 synthesis) and the PIKfyve activator ArPIKfyve. The triple PIKfyve-ArPIKfyve-Sac3 (PAS) complex ensures the PtdIns(3,5)P2 homeostatic control by rapid turnover counterbalancing locally elevated PtdIns(3,5)P2. PtdIns(3,5)P2, a low abundance PI comprising as little as 0.8% of total PIs in mammalian cells, mediates essential aspects of endocytic membrane homeostasis and coordinates fission and fusion events in the multivesicular endosomal system of mammalian cells <cite>Ikonomov09</cite>.

=== References ===
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