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The pharmacological profile of the vesicular monoamine transporter resembles that of multidrug transporters
Author(s) -
Yelin Rodrigo,
Schuldiner Shimon
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)01346-6
Subject(s) - vesicular monoamine transporter , monoamine neurotransmitter , transporter , biology , biochemistry , vesicular monoamine transporter 2 , atp binding cassette transporter , vesicular transport protein , synaptic vesicle , neurotransmitter transporter , reuptake , microbiology and biotechnology , chemistry , serotonin , vesicle , receptor , membrane , gene
Vesicular neurotransmitter transporters function in synaptic vesicles and other subcellular organelles and they were thought to be involved only in neurotransmitter storage. Several findings have led us to test novel aspects of their function. Cells expressing a c‐DNA coding for one of the rat monoamine transporters (VMAT1) become resistant to the neurotoxin N ‐methyl‐4‐phenylpyridinium (MPP + ) [Liu et al. (1992) Cell, 70, 539–551]. The basis of the resistance is the VMAT1‐mediated transport and sequestration of the toxin into subcellular compartments. In addition, the deduced sequence of VMAT1 predicts a protein that shows a distinct homology to a class of bacterial drug resistance transporters (TEXANs) that share some substrates with mammalian multidrug resistance transporters (MDR) such as the P‐glycoprotein. These findings induced us to test whether compounds that are typically transported by MDR interact also with vesicular transporters. The use of [ 3 H]reserpine binding to determine drug interactions with VMAT allowed assessment of the ability of various drugs to bind to the substrate site of the transporter. Cytotoxic compounds such as ethidium, isometamidium, tetraphenylphosphonium, rhodamine, tacrine and doxorubicin, interact specifically with vesicular monoamine transporters. Verapamil, a calcium channel blocker, is also a competitive inhibitor of transport. In the case of rhodamine, fluorescence measurements in digitonin‐permeabilized cells demonstrated ATP‐dependent VMAT‐mediated transport. The results imply that even though the bacterial and vesicular transporters are structurally different from the P‐glycoprotein, they share a similar substrate range. These findings suggest a novel possible way of protection from the effects of toxic compounds by removal to subcellular compartments.