phospholipids are found in vesicle walls of a cell.
phospholipids are found in vesicle walls of a cell.
where do you find phospholipids in a cell?
vesicle walls
in contrast, the linker domain is composed of α helices supplied by the two catalytic domains: each domain contributes five helices from their n termini and one from a helix that spans both the catalytic domain and the linker domain. at the center of the linker domain resides an 8 by 35 å hydrophobic tunnel with two phospholipids bound at each end. the head of each phospholipid points outward towards solution while the tails are embedded within the enzyme. the function of this hydrophobic tunnel is unknown, though two hypotheses have been postulated concerning its utility. the first is that the binding of the terminal phospholipids alters the conformation of the active sites, implying that the tunnel acts as an effector, only allowing the enzyme to be active in certain areas of the cell. the second hypothesis postulates that the tunnel regulates lipid membrane rigidity through its degradation of phenolic hydrocarbons and ability to bind to other lipids. studies have shown that phenolic hydrocarbons affect the functional and structural properties of cell membranes. 1,2-ctd degrades phenolic hydrocarbons key to the synthesis lipid membranes. therefore, 1,2-ctd may bind to the cell lipid membrane via its terminal phospholipids and thus have greater access to the phenolic hydrocarbons vital in lipid membrane structure.
catechol 1,2-dioxygenase
protein s can bind to negatively charged phospholipids via the carboxylated gla domain. this property allows protein s to function in the removal of cells which are undergoing apoptosis. apoptosis is a form of cell death that is used by the body to remove unwanted or damaged cells from tissues. cells, which are apoptotic (i.e. in the process of apoptosis), no longer actively manage the distribution of phospholipids in their outer membrane and hence begin to display negatively charged phospholipids, such as phosphatidyl serine, on the cell surface. in healthy cells, an atp (adenosine triphosphate)-dependent enzyme removes these from the outer leaflet of the cell membrane. these negatively charged phospholipids are recognized by phagocytes such as macrophages. protein s can bind to the negatively charged phospholipids and function as a bridging molecule between the apoptotic cell and the phagocyte. the bridging property of protein s enhances the phagocytosis of the apoptotic cell, allowing it to be removed 'cleanly' without any symptoms of tissue damage such as inflammation occurring.
protein s