ISSN:
1432-1424
Keywords:
lepidopteran midgut
;
alanine transport
;
amino acid transport
;
K-cotransport
;
brush border membrane vesicles
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary In brush border membrane vesicles from the midgut ofPhilosamia cynthia larvae (Lepidoptera) thel- andd-alanine uptake is dependent on a potassium gradient and on transmembrane electrical potential difference. Each isomer inhibits the uptake of the other form: inhibition ofl-alanine uptake byd-alanine is competitive, whereas inhibition ofd-alanine uptake byl-alanine is noncompetitive. Transstimulation experiments as well as the different pattern of specificity to cations suggest the existence of two transport systems. Kinetic parameters for the two transporters have been calculated both when Kout〉Kin and Kout=Kin.d-alanine is actively transported also by the whole midgut, but it is not metabolized by the intestinal tissue.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01868716
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