Vac14 Homolog (VAC14)

The content of phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P2) in endosomal membranes changes dynamically with fission and fusion events that generate or absorb intracellular transport vesicles. VAC14 is a component of a trimolecular complex that tightly regulates the level of PtdIns(3,5)P2. Other components of this complex are the PtdIns(3,5)P2-synthesizing enzyme PIKFYVE and the PtdIns(3,5)P2 phosphatase FIG4 . VAC14 functions as an activator of PIKFYVE. The deduced 221-amino acid TRX protein is predominantly hydrophilic in its C-terminal region. Northern blot analysis of human tissues detected a major 3.5-kb TRX transcript in all tissues examined, namely brain, heart, lung, liver, pancreas, kidney, skeletal muscle, and placenta. However, Western blot analysis detected TRX expression only in lymphocytes and lymphocytic-derived cell lines.