Phosphatidylinositol (or Inositol Phospholipid) consists of a family of lipids as illustrated on the right, where red is x, blue is y, and black is z, in the context of independent variation, a class of the phosphatidylglycerides. In such molecules the isomer of the inositol group is assumed to be the myo- conformer unless otherwise stated. Typically phosphatidylinositols form a minor component on the cytosolic side of eukaryotic cell membranes. The phosphate group gives the molecules a negative charge at physiological pH.
The form of phosphatidylinositol comprising the isomer muco-inositol acts as a sensory receptor in the taste function of the sensory system. In this context it is often referred to as PtdIns, but that does not imply any molecular difference from phosphatidylinositols comprising the myo- conformers of inositol.
Biosynthesis of phosphatidylinositol catalyzed by phosphatidylinositol synthase. Figure adapted from Christopher, K.; van Holde, K.E.; Ahern, Kevin G. Biochemistry Third Edition. Pearson Education, Inc: Singapore, 2005; p 678.[1]
The synthesis of phosphatidylinositol in the laboratory is catalyzed by phosphatidylinositol synthase and involves CDP-diacylglycerol and L-myo-inositol.[1]
Chemistry
PI has a polar and non-polar region, making the lipid an amphiphile. Phosphatidylinositol is classified as a glycerophospholipid that contains a glycerol backbone, two non-polar fatty acid tails, a phosphate group substituted with an inositol polar head group.
The most common fatty acids of phosphoinositides are stearic acid in the SN1 position and arachidonic acid, in the SN2 position. Hydrolysis of phosphoinositides yield one mole of glycerol, two moles of fatty acids, one mole of inositol and one, two, or three moles of phosphoric acids, depending on the number of phosphates on the inositol rings. Phosphoinositides are regarded as the most acidic phospholipids.
The specific fatty acids of PtdIns, and their conformation, employed in the sensory neurons has not been elucidated.
Phosphoinositides
Phosphorylated forms of phosphatidylinositol (PI) are called phosphoinositides and play important roles in lipid signaling, cell signaling and membrane trafficking. The inositol ring can be phosphorylated by a variety of kinases on the three, four and five hydroxyl groups in seven different combinations. However, the two and six hydroxyl groups are typically not phosphorylated due to steric hindrance.
All seven variations of the following phosphoinositides have been found in animals:
^ abMathews, Chrisotphe K.; van Holde, K.E.; Ahern, Kevin G. (2005). Biochemistry Third Edition.
^Muller-Roeber B, Pical C (2002). Inositol Phospholipid Metabolism in Arabidopsis. Characterized and Putative Isoforms of Inositol Phospholipid Kinase and Phosphoinositide-Specific Phospholipase C.
phosphatidylinositol, inositol, phospholipid, consists, family, lipids, illustrated, right, where, blue, black, context, independent, variation, class, phosphatidylglycerides, such, molecules, isomer, inositol, group, assumed, conformer, unless, otherwise, sta. Phosphatidylinositol or Inositol Phospholipid consists of a family of lipids as illustrated on the right where red is x blue is y and black is z in the context of independent variation a class of the phosphatidylglycerides In such molecules the isomer of the inositol group is assumed to be the myo conformer unless otherwise stated Typically phosphatidylinositols form a minor component on the cytosolic side of eukaryotic cell membranes The phosphate group gives the molecules a negative charge at physiological pH Phosphatidylinositol NamesOther names PI PtdInsIdentifiersChEBI CHEBI 28874DrugBank DB02144PropertiesChemical formula C47H83O13PMolar mass 886 56 g mol neutral with fatty acid composition 18 0 20 4Except where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa Y verify what is Y N Infobox references The form of phosphatidylinositol comprising the isomer muco inositol acts as a sensory receptor in the taste function of the sensory system In this context it is often referred to as PtdIns but that does not imply any molecular difference from phosphatidylinositols comprising the myo conformers of inositol The phosphatidylinositol can be phosphorylated to form phosphatidylinositol phosphate PI 4 P referred to as PIP in close context or informally phosphatidylinositol bisphosphate PIP2 and phosphatidylinositol trisphosphate PIP3 All lipids based on phosphatidylinositol are known as inositides or sometimes phosphoinositides Contents 1 Biosynthesis 2 Chemistry 3 Phosphoinositides 4 See also 5 References 6 Additional images 7 External linksBiosynthesis Edit Biosynthesis of phosphatidylinositol catalyzed by phosphatidylinositol synthase Figure adapted from Christopher K van Holde K E Ahern Kevin G Biochemistry Third Edition Pearson Education Inc Singapore 2005 p 678 1 The synthesis of phosphatidylinositol in the laboratory is catalyzed by phosphatidylinositol synthase and involves CDP diacylglycerol and L myo inositol 1 Chemistry EditPI has a polar and non polar region making the lipid an amphiphile Phosphatidylinositol is classified as a glycerophospholipid that contains a glycerol backbone two non polar fatty acid tails a phosphate group substituted with an inositol polar head group The most common fatty acids of phosphoinositides are stearic acid in the SN1 position and arachidonic acid in the SN2 position Hydrolysis of phosphoinositides yield one mole of glycerol two moles of fatty acids one mole of inositol and one two or three moles of phosphoric acids depending on the number of phosphates on the inositol rings Phosphoinositides are regarded as the most acidic phospholipids The specific fatty acids of PtdIns and their conformation employed in the sensory neurons has not been elucidated Phosphoinositides EditPhosphorylated forms of phosphatidylinositol PI are called phosphoinositides and play important roles in lipid signaling cell signaling and membrane trafficking The inositol ring can be phosphorylated by a variety of kinases on the three four and five hydroxyl groups in seven different combinations However the two and six hydroxyl groups are typically not phosphorylated due to steric hindrance All seven variations of the following phosphoinositides have been found in animals Phosphatidylinositol monophosphates Phosphatidylinositol 3 phosphate also known as PtdIns3P or PI 3 P Phosphatidylinositol 4 phosphate also known as PtdIns4P or PI 4 P Phosphatidylinositol 5 phosphate also known as PtdIns5P or PI 5 PPhosphatidylinositol bisphosphates Phosphatidylinositol 3 4 bisphosphate also known as PtdIns 3 4 P2 or PI 3 4 P2 Phosphatidylinositol 3 5 bisphosphate also known as PtdIns 3 5 P2 or PI 3 5 P2 Phosphatidylinositol 4 5 bisphosphate also known as PtdIns 4 5 P2 PI 4 5 P2 or often simply referred to as PIP2Phosphatidylinositol trisphosphate Phosphatidylinositol 3 4 5 trisphosphate also known as PtdIns 3 4 5 P3 or PI 3 4 5 P3These phosphoinositides are also found in plant cells with the exception of PIP3 2 See also Edit Wikimedia Commons has media related to Phosphatidylinositol PI 3 kinase Inositol phosphate Phosphatidylinositol 3 phosphate Phosphatidylinositol 4 phosphate Phosphatidylinositol 5 phosphate Phosphatidylinositol 3 4 bisphosphate Phosphatidylinositol 3 5 bisphosphate Phosphatidylinositol 4 5 bisphosphate Inositol 1 4 5 triphosphate Phosphatidylinositol 3 4 5 trisphosphate inositol pentakisphosphate inositol hexaphosphate inositol triphosphate receptorReferences Edit a b Mathews Chrisotphe K van Holde K E Ahern Kevin G 2005 Biochemistry Third Edition Muller Roeber B Pical C 2002 Inositol Phospholipid Metabolism in Arabidopsis Characterized and Putative Isoforms of Inositol Phospholipid Kinase and Phosphoinositide Specific Phospholipase C Additional images Edit Membrane lipids Phosphatidyl inositol Inositol GlycerolExternal links EditPhosphatidylinositols at the US National Library of Medicine Medical Subject Headings MeSH Phosphatidylinositol at Lipid Library Retrieved from https en wikipedia org w index php title Phosphatidylinositol amp oldid 1061429407, wikipedia, wiki, book, books, library,
