Molecule of the Month: Neurotransmitter Transporters
Neurotransmitters are transported out of nerve synapses to end a signal transmission
Ending the Message
Prolonging the Message
Exploring the Structure
Leucine Transporter LeuT (PDB entries 3f3e, 3tt1 and 3tt3)
Another well-studied bacterial transporter, which is related to the dopamine transporter, has revealed several of the steps in the molecular pumping cycle. Three structures are shown here: one that is open to the outside of the cell, one with a molecule and several ions caught in the middle of being transported, and one that is open to the inside of the cell (PDB entries 3tt1 , 3f3e and 3tt3 ). Several alpha helices, shown here in bright turquoise, form a tunnel with a constriction at the center that performs the specific pumping task. To see an animation of this protein in action, click on the image for an interactive Jmol.
Topics for Further Discussion
- Try using one of the 3D viewers at the PDB to look at the specific interactions between transporters and the molecules that they transport, for instance, the aspartates bound in the transport site of PDB entry 2nwx.
- The function of the dopamine transporter is modulated by cholesterol--you can see how it binds in PDB entry 4m48.
Related PDB-101 Resources
- Browse Cellular Signaling
- Browse Drug Action
- Browse Transport
- P. J. Focke, X. Wang & H. P. Larsson (2013) Neurotransmitter transporters: structure meets function. Structure 21, 694-705.
- 4m48: A. Penmatsa, K. H. Wang & E. Gouaux (2013) X-ray structure of dopamine transporter elucidates antidepressant mechanism. Nature 503, 85-89.
- 3tt1, 3tt3: H. Krishnamurthy & E. Gouaux (2012) X-ray structures of LeuT in substrate-free outward-open and apo inward-open states. Nature 481, 469-474.
- 3f3e: S. K. Singh, C. L. Piscitelli, A. Yamashita & E. Gouaux (2008) A competitive inhibitor traps LeuT in an open-to-out conformation. Science 322, 1655-1661.
- 2nwx: O. Boudker, R. M. Ryan, D. Yernool, K. Shimamoto & E. Gouaux (2007) Coupling substrate and ion binding to extracellular gate of a sodium-dependent aspartate transporter. Nature 445, 387-393.
March 2014, David Goodselldoi:10.2210/rcsb_pdb/mom_2014_3