Sequential ordered mechanism for the sodium-glutamate transport in intestinal brush border membrane vesicles.
The glutamate/aspartate carrier localized in the brush-border membrane vesicles from enterocytes is known as a transport system catalyzing a sodium-substrate cotransport driven by the sodium gradient across the membrane. The kinetics of this transport system is studied by analogy with an enzymatic bi-substrate reaction. The results of this approach can be summarized as follows: (1) The dependence of the L-glutamate transport rate on the sodium concentration is sigmoidal, and the stoichiometry of the transport is 2 Na+/1 glutamate/1 carrier molecule. (2) The mechanism is sequential ordered, with L-glutamate binding after both the sodium cations. In addition, there is a very high degree of cooperativity between the two sodium binding sites.
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Dipartimento Farmaco-biologico, Università degli Studi di Bari, Italy.
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D027322:Amino Acid Transport System X-AG; D000818:Animals; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D050491:Glutamate Plasma Membrane Transport Proteins; D018698:Glutamic Acid / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism*; D017136:Ion Transport; D007700:Kinetics; D008871:Microvilli / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism*; D027981:Symporters
D027322:Amino Acid Transport System X-AG; D002352:Carrier Proteins; D050491:Glutamate Plasma Membrane Transport Proteins; D027981:Symporters; D018698:Glutamic Acid; D012964:Sodium