Editing Peripheral membrane protein (section)

===Specific protein–lipid binding===
[[Image:1h6h.png|thumb|right|250px| P40phox PX domain of NADPH oxidase Middle plane of the lipid bilayer – black dots. Boundary of the hydrocarbon core region – blue dots (intracellular side). Layer of lipid phosphates – yellow dots.]]
Some [[cytosolic]] proteins are recruited to different cellular membranes by recognizing certain types of lipid found within a given membrane.<ref name="Cho">{{cite journal | vauthors = Cho W, Stahelin RV | title = Membrane-protein interactions in cell signaling and membrane trafficking | journal = Annual Review of Biophysics and Biomolecular Structure | volume = 34 | pages = 119–151 | date = June 2005 | pmid = 15869386 | doi = 10.1146/annurev.biophys.33.110502.133337 | name-list-style = amp }}</ref> Binding of a protein to a specific lipid occurs via specific membrane-targeting structural domains that occur within the protein and have specific binding pockets for the [[phospholipids#Amphipathic character|lipid head groups]] of the lipids to which they bind. This is a typical [[biochemistry|biochemical]] protein–[[Ligand (biochemistry)|ligand]] interaction, and is stabilized by the formation of intermolecular [[hydrogen bond]]s, [[van der Waals force|van der Waals interactions]], and [[hydrophobic|hydrophobic interactions]] between the protein and lipid [[ligand]]. Such complexes are also stabilized by the formation of ionic bridges between the [[aspartate]] or [[glutamate]] residues of the protein and lipid phosphates via intervening [[calcium]] ions (Ca<sup>2+</sup>).<!-- ref --> Such ionic bridges can occur and are stable when ions (such as Ca<sup>2+</sup>) are already bound to a protein in solution, prior to lipid binding. The formation of ionic bridges is seen in the protein–lipid interaction between both protein [[C2 domain|C2 type domains]] and [[annexin]]s.<!-- ref -->.