The unidirectional transport of proline by midgut epithelium cells of the tobacco hornworm, Manduca sexta, was investigated in brush border membrane vesicles. Both K.+-stimulated and K+-insensitive transport pathways were identified. Analyses of K+-dependent proline transport revealed 1:1 ratio of K+ to proline, a Km of 13 mM for K+ and a decrease in both Km (from 18 mM to 3mM) and Vmax (from 37 nmol/mg protein/min to 10 nmol/mg protein/min) for proline in the presence of a K+ gradient. The profiles of cis-inhibition by other amino acids demonstrated that proline is transported into midgut cells by a transport system that is shared by other neutral amino acids.
|Number of pages||7|
|Journal||Comparative Biochemistry and Physiology -- Part A: Physiology|
|State||Published - Apr 1994|
Bibliographical noteFunding Information:
Acknowledgemenfs-The authors thank Professors J. J. Neal, J. Stuart and C. Y. Oseto for critical review of the manuscript. This research was supported by United States Department of Agriculture Competitive Research Grant No. 88-37153-4098 to A. I. Aronson and P.E.D. This is Journal Paper No 13,630 from the Indiana Agricultural Experiment Station.
- Brush border membrane vesicle
- Manduca sexta
- Proline transport
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