ISSN:
1432-1424
Keywords:
lepidopteran larvae midgut
;
basic amino-acid transport
;
K+ cotransport
;
transstimulation
;
brush-border membrane vesicles
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary Experiments performed on isolated midgut demonstrate that the model proposed for the absorption of neutral amino acids in the K+-transporting intestinal epithelium of lepidopteran larvae applies also to the transport of the basic amino acids histidine and lysine. The characteristics of these K+-basic amino-acid cotransports have been studied in brush-border membrane vesicles. Histidine and lysine are transported by different transport agencies, which share, to a different degree, a high sensitivity to transmembrane electrical potential difference. Kinetic analysis showed thatK m for histidine and lysine increased 10-fold and three-fold, respectively, whereasV max was only slightly modified when the electrical potential difference was abolished. The relationship between potassium concentration and histidine uptake indicates a cooperative binding of more than one potassium to the transporter. Countertransport experiments with glutamine as elicitor show that histidine and glutamine are transported through the same system.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01871212
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