Symporters
A symporter is one of two types of coupled transporters that are used in active transport. It moves molecules through a phospholipid bilayer, against its concentration gradient by harnessing the energy released from a second molecule that is moving with its concentration gradient. Molecules wish to move from a high to a low concentration so if the molecule is needed to be moved from a low to a high concentration simple or facilitated diffusion cannot be used. Instead, either a coupled transporter or a unitransporter can be used. The two types of coupled transporters are an antiporter, the two molecules move in opposite directions or symporters where the target molecule (that needs to be moved) and the molecule the energy is being taken from are moving in the same direction.[1] An example of a symporter is moving glucose up its concentration gradient (often referred to as uphill movement) by using the energy from the movement of sodium ions that are moving down their gradient (downhill movement).[2]
All of these types of transporter are types of carrier protein and use energy by hydrolysing ATP to ADP and a phosphate.[3]
References
- ↑ •B. Alberts et. al (2008) Molecular Biology of The Cell, 5th Edition, New York: Garland Science (pg 656)
- ↑ •B. Alberts et. al (2008) Molecular Biology of The Cell, 5th Edition, New York: Garland Science (pg 657)
- ↑ •B. Alberts et. al (2008) Molecular Biology of The Cell, 5th Edition, New York: Garland Science (pg G:37)