The synaptic vesicle protein B0AT3 (SLC6A17) catalyzes sodium-coupled neutral amino acid transport
Abstract/Contents
- Abstract
- The SLC6 family of structurally related, Na+-dependent transporter proteins is responsible for presynaptic reuptake of the majority of neurotransmitters including dopamine, serotonin, norepinephrine, glycine, and GABA. Additional family members transport creatine, osmolytes, or amino acids, but several transporters remain orphans with unknown function. SLC6A17 is an orphan transporter in the SLC6 family that was first identified in the early 1990s. It is expressed exclusively in the nervous system and specifically on synaptic vesicles in glutamatergic and some GABAergic neurons. Despite extensive efforts by other research groups, no substrate or transport mechanism has been reported for SLC6A17. In this dissertation, I describe the functional characterization of SLC6A17 and discuss the potential physiological relevance of SLC6A17 as a synaptic vesicle protein. I show that endogenous and heterologous SLC6A17 localizes to vesicular populations in cultured rat hippocampal neurons and mammalian cell lines. I then use a combination of molecular manipulations to increase expression of the SLC6A17 protein at the plasma membrane and directly demonstrate that it catalyzes neutral amino acid transport. The transport characteristics of SLC6A17 resemble those of its closely related family member B0AT2 (SLC6A15). The substrate profile of the SLC6A17-dependent activity, similar to that of B0AT2, includes a sub-millimolar apparent affinity for proline and leucine and a low millimolar apparent affinity for glutamine. SLC6A17, like B0AT2, exhibits a Na+-dependent, Cl--independent transport activity that is inhibited at low pH. These similarities in substrate profile and transport mechanism suggest that SLC6A17 and B0AT2 have redundant roles, leading to our naming the SLC6A17 protein as B0AT3. Finally, I examine the pH sensitivity of B0AT3-mediated transport using live imaging techniques. My analysis suggests that B0AT3 and B0AT2 do not couple substrate movement with proton flux, supporting an uncoupled role for proton inhibition. This characterization of B0AT3 offers insights on neurotransmitter metabolism and also highlights mechanistic differences among the structurally related, but functionally divergent, SLC6 proteins.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2010 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Salvia, Kimberly Ann |
|---|---|
| Associated with | Stanford University, Department of Neurosciences. |
| Primary advisor | Reimer, Richard J |
| Thesis advisor | Reimer, Richard J |
| Thesis advisor | Maduke, Merritt C, 1966- |
| Thesis advisor | Tsien, R. W. (Richard W.) |
| Thesis advisor | Yang, Yanmin, Ph. D |
| Advisor | Maduke, Merritt C, 1966- |
| Advisor | Tsien, R. W. (Richard W.) |
| Advisor | Yang, Yanmin, Ph. D |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Kimberly A. Salvia. |
|---|---|
| Note | Submitted to the Department of Neurosciences. |
| Thesis | Ph.D. Stanford University 2010 |
| Location | electronic resource |
Access conditions
- Copyright
- © 2010 by Kimberly Ann Salvia
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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