Carrier Protein

  • Carrier proteins are pr´╗┐oteins that transport certain substances across a biological membrane, in facilitated diffusion
    • Carrier proteins transport molecules from an area of higher concentration on one side of the membrane to an area of lower concentration on the opposite side
external image cell_membrane_channel1.jpg

  • Carrier proteins are needed by a cell to transport molecules that are not soluable in lipds , preventing them to pass through the membrane
    • Carrier proteins assist these molecules in moving to another side of the cell membrane
  • Process
    • First the carrier protein binds to the molecule for transport
    • Second, the carrier protein changes shape, to shield the molecule from the hydrophobic tail of the bilayer in the membrane
    • Then the molecule gets transported to the other side of the cell membrane and is released from the carrier protein´╗┐´╗┐
    • Lastly, the carrier protein retains its original shape
    • external image Image132.gif
  • Carrier Proteins help with passive transport, but also hlpe with active transport
    • Carrier proteins that are involved in active transport are called "Pumps" because they move the substances up and down the concentration gradients
    • An example of a carrier protein involved in active transport is a sodium-potassium pump
      • This particular pump transports Na+ ions and K+ ions through the concentration gradients

external image Active%2BTransport.jpgIon Pump
Alcamo,Edward.Modern Biology.Austin:Haolt, Rinehart, and Winston, 1999.1138.Print.
("Sodium-Potassium Pump")