The field of membrane biophysics is at a stage where experimentation in well-controlled artificial model systems are still very valuable and are often the only way to gain some basic understanding of lipidic molecules, their interactions and their physicochemical properties. In this book, I thus focus on one particular and very special family of glycophospholipids called Phosphatidylinositol (PtdIns) which are located at the PM and other organelles' membranes. Phosphatidylinositol and its derivatives, such as PIP2 which is an exceptionally extraordinary lipid, play a crucial role in many aspects of cell physiology and cellular signaling .One of the ways that PtdIns interact with other molecules, and with those in the cytoplasm in particular, is through their head group. Based on an inositol ring, it allows for several degrees of phosphorylation which gives rise to a highly negatively charged lipid. Different models have been developed to describe the electrostatic potential generated by these charged lipids. To the best of my knowledge, there is no model as yet describing the mechanical properties associated with their lateral organization and their interactions.