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I was just wondering whether cocaine, once reaching a synapse, binds to a DAT (Dopamine transporter) competitively or non competitively, or neither of them?

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Cocaine binds competitively to DAT, though not in precisely the same binding site, rather there is overlap, and many of the same amino acids are involved in binding of each.

Amphetamine and benztropines also bind in the same region.

Beuming, T., Kniazeff, J., Bergmann, M. L., Shi, L., Gracia, L., Raniszewska, K., ... & Loland, C. J. (2008). The binding sites for cocaine and dopamine in the dopamine transporter overlap. Nature neuroscience, 11(7), 780-789.

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    $\begingroup$ Just to further support this answer..from the last sentence of the abstract in the article: "Our data demonstrate the molecular basis for the competitive inhibition of dopamine transport by cocaine." $\endgroup$ – Charles Jul 30 '17 at 23:20
  • $\begingroup$ Is this overlap also present when dopamine binds to the dopamine transporter? $\endgroup$ – ModoUnreal Aug 5 '17 at 18:10
  • $\begingroup$ @ModoUnreal I'm not sure what you are asking- this is all referring to competitive binding with respect to binding of dopamine. When you have competitive antagonism you can't really bind substrate and antagonist simultaneously, that's the whole meaning of competitive binding: they sit in the same place. $\endgroup$ – Bryan Krause Aug 5 '17 at 19:51
  • $\begingroup$ As in does dopamine overlap with the dopamine transporter when it binds to it, like cocaine does? Apologies for the confusion. $\endgroup$ – ModoUnreal Aug 6 '17 at 8:22
  • $\begingroup$ Overlapping is referring to the binding sites for dopamine and the binding sites for cocaine on the transporter. Each binds to some of the same amino acids so we say they are overlapping. It doesn't make any sense to say whether either overlaps with the transporter: the transporter isn't binding itself. $\endgroup$ – Bryan Krause Aug 6 '17 at 16:43

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