Do neutral amino acids and their N-methylated analogues share the same Na-dependent carrier in brush-border membrane from the eel intestine?

• Published in: Comparative Biochemistry and Physiology Part A: Physiology
• Main Authors: G. CASSANO, P. A. RAMIRES, MAFFIA, Michele, VILELLA, Sebastiano, STORELLI, Carlo
• Other Authors: G., Cassano, Maffia, Michele, P. A., Ramire, Vilella, Sebastiano, Storelli, Carlo
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1990
• Subjects: Anguilla anguilla
• Online Access: http://hdl.handle.net/11587/105211; https://doi.org/10.1016/0300-9629(90)90035-Q

Brush-border membrane (BBM) vesicles were prepared from the intestine of yellow eels (Anguilla anguilla) by selective precipitation of all other cellular components. The activity of a Na-substrate cotransporter was evaluated by measuring the rate of decay of an inside negative membrane potential with a voltage-sensitive fluorescent dye; the rate of fluorescence quenching decay in the presence of Na was subtracted from the rate of decay in the presence of both cosubstrates. The kinetics of Na-dependent amino acid transport systems were then determined for the neutral amino acids and their N-methylated analogues. It was concluded that N-methylglycine, N-methylalanine and α-(methylamino)-isobutyric acid are transported by the Na-dependent carrier responsible for proline translocation, which is distinct from the one responsible for glycine, alanine and α-aminoisobutyric acid translocations.