# Membrane Proteins --- **Membrane proteins** are [[protein|proteins]] that are associated in a cell's [[plasma membrane]]. They are amphipathic, so they can integrate into lipid bilayers, while still being able to interact with the parts outside of the membrane as well. The part that is inside the membrane is [[polar and nonpolar|hydrophobic]], and the part on the outside of the membrane is [[polar and nonpolar|hydrophilic]]. hydrophilic **Integral membrane proteins** span the whole width of the membrane. (Apparently some of them don't go all the way through, but most do.) For these proteins, the outside edges of these channels are hydrophobic, but the inside edge of them is hydrophilic. They function as transport proteins, enzymes or receptors. **Peripheral membrane proteins** are only anchored in one side or the other. They function as enzymes or motor proteins (idk what that means). ## Function Membrane proteins have a wide variety of important functions, which can be summed up in six categories: - [[membrane transport protein|transport]] of other molecules - channels - carriers - pumps - [[cell signaling]] - contact signaling - chemical signaling - g protein-linked receptors - ligand-receptor signaling - [[enzyme|enzymatic activity]] - [[cell junction]] - attaching to the [[extracellular matrix|ECM]] - identity markers ## Fluid Mosaic Model The **fluid mosaic model** is that the molecules that make up the biological membrane are constantly moving relative to each other. It's a horizontal motion, one phospholipid won't go from the inside layer to the outside layer. The proteins that are embedded in the membrane are not static, they're all in motion. ___