Phosphatidylinositol 5-phosphate
Encyclopedia
Phosphatidylinositol 5-phosphate (PtdIns5P or PI5P) is one of the seven phosphoinositides
, and is the last to have been discovered to be naturally occurring.
In 1997 Lucia Rameh, while working as a postdoctoral fellow with Lewis C. Cantley
observed that the enzymes referred to as type II PIP-kinases did not utilize PtdIns4P as a substrate (as had been proposed). In fact, they required PtdIns5P as a substrate to produce PtdIns(4,5)P2. The observation immediately suggested that cells must contain a natural pool of PtdIns(5)P, a prediction that was verified by Rameh, Cantley, and colleagues.
The function of PtdIns5P remains uncertain, especially since no specific PtdIns5P-binding proteins have been unambiguously identified. There is some thought that it may function in membrane trafficking from late endosomes to the plasma membrane.
Phosphatidylinositol
Phosphatidylinositol is a negatively charged phospholipid and a minor component in the cytosolic side of eukaryotic cell membranes....
, and is the last to have been discovered to be naturally occurring.
In 1997 Lucia Rameh, while working as a postdoctoral fellow with Lewis C. Cantley
Lewis C. Cantley
Lewis C. Cantley is an American cell biologist and biochemist and a professor in the Departments of Systems Biology and Medicine at Harvard Medical School, and the Director of Cancer Research at the Beth Israel Deaconess Medical Center, in Boston, Massachusetts...
observed that the enzymes referred to as type II PIP-kinases did not utilize PtdIns4P as a substrate (as had been proposed). In fact, they required PtdIns5P as a substrate to produce PtdIns(4,5)P2. The observation immediately suggested that cells must contain a natural pool of PtdIns(5)P, a prediction that was verified by Rameh, Cantley, and colleagues.
The function of PtdIns5P remains uncertain, especially since no specific PtdIns5P-binding proteins have been unambiguously identified. There is some thought that it may function in membrane trafficking from late endosomes to the plasma membrane.