Transporter or Channel?

Transporters and channels are considered to operate in a different way. A channel is like an open door in the membrane, whereas transporters are likened to sliding doors with swipe card access. Stefan Bröer's group together with German colleagues have studied a transporter which also behaves like a channel. The protein is involved in the release of the neurotransmitter precursor glutamine from brain astrocytes. Transport properties were studied by microelectrodes, which detect changes of the membrane potential and of the intracellular pH. The studies revealed a pore in the transporter that can be used by glutamine itself but also by ions in a similar way as they move through an ion channel.

Schneider, HP, Broer, S, Broer, A, and Deitmer, JW (2007) Heterologous expression of the glutamine transporter SNAT3 in Xenopus Oocytes is associated with four modes of uncoupled transport. J Biol Chem 282: 3788-98

Further Info Online:

• http://www.jbc.org/cgi/content/full/282/6/3788