| First Author | Rameh LE | Year | 1997 |
| Journal | Nature | Volume | 390 |
| Issue | 6656 | Pages | 192-6 |
| PubMed ID | 9367159 | Mgi Jnum | J:297456 |
| Mgi Id | MGI:6478527 | Doi | 10.1038/36621 |
| Citation | Rameh LE, et al. (1997) A new pathway for synthesis of phosphatidylinositol-4,5-bisphosphate. Nature 390(6656):192-6 |
| abstractText | Phosphatidylinositol-4,5-bisphosphate (PtdIns-4,5-P2), a key molecule in the phosphoinositide signalling pathway, was thought to be synthesized exclusively by phosphorylation of PtdIns-4-P at the D-5 position of the inositol ring. The enzymes that produce PtdIns-4,5-P2 in vitro fall into two related subfamilies (type I and type II PtdInsP-5-OH kinases, or PIP(5)Ks) based on their enzymatic properties and sequence similarities'. Here we have reinvestigated the substrate specificities of these enzymes. As expected, the type I enzyme phosphorylates PtdIns-4-P at the D-5 position of the inositol ring. Surprisingly, the type II enzyme, which is abundant in some tissues, phosphorylates PtdIns-5-P at the D-4 position, and thus should be considered as a 4-OH kinase, or PIP(4)K. The earlier error in characterizing the activity of the type II enzyme is due to the presence of contaminating PtdIns-5-P in commercial preparations of PtdIns-4-P. Although PtdIns-5-P was previously thought not to exist in vivo, we find evidence for the presence of this lipid in mammalian fibroblasts, establishing a new pathway for PtdIns-4,5-P2 synthesis. |
