FIG4 phosphoinositide 5-phosphatase
The FIG4 gene provides instructions for making a protein called Fig4, whose function is not well understood. Researchers believe that the Fig4 protein plays a role in regulating a compound called phosphatidylinositol-3,5-bisphosphate, or PtdIns(3,5)P(2). This compound is involved in the movement of small sac-like structures called vesicles that transport certain substances within cells (vesicle trafficking). The Fig4 protein also seems to help in the survival of nerve cells (neurons).
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At least five mutations in the FIG4 gene have been identified in individuals with Charcot-Marie-Tooth disease type 4J. One of these mutations replaces the protein building block (amino acid) isoleucine with the amino acid threonine at position 41 (written as Ile41Thr or I41T). This mutation has been identified in one copy of the FIG4 gene in everyone with Charcot-Marie-Tooth disease type 4J. In addition, each individual has another mutation in the other copy of their FIG4 gene. These mutations change single amino acids in the protein sequence or result in an abnormally short, non-functional protein. Researchers are working to determine how mutations in the FIG4 gene lead to the specific signs and symptoms of Charcot-Marie-Tooth disease type 4J.
- FIG4 homolog (S. cerevisiae)
- FIG4 homolog, SAC1 lipid phosphatase domain containing (S. cerevisiae)
- Sac domain-containing inositol phosphatase 3