Abstract
Amino acids enter rabbit jejunal brush border membrane vesicles via three major transport systems: (1) simple passive diffusion; (2) Na-independent carriers; and (3) Na-dependent carriers. The passive permeability sequence of amino acids is very similar to that observed in other studies involving natural and artificial membranes. Based on uptake kinetics and cross-inhibition profiles, at least two Na-independent and three Na-dependent carrier-mediated pathways exist. One Na-independent pathway, similar to the classical L system, favors neutral amino acids, while the other pathway favors dibasic amino acids such as lysine. One Na-dependent pathway primarily serves neutral l-amino acids including 2-amino-2-norbornanecarboxylic acid hemihydrate (BCH), but not β-alanine or α-methylaminoisobutyric acid (MeAIB). Another Na-dependent route favors phenylalanine and methionine, while the third pathway is selective for imino acids and MeAIB. Li is unable to substitute for Na in these systems. Cross-inhibition profiles indicated that none of the Na-dependent systems conform to classical A or ACS paradigms. Other notable features of jejunal brush border vesicles include (1) no β-alanine carrier, and (2) no major proline/glycine interactions.
Original language | English (US) |
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Pages (from-to) | 213-225 |
Number of pages | 13 |
Journal | The Journal of Membrane Biology |
Volume | 66 |
Issue number | 1 |
DOIs | |
State | Published - Dec 1982 |
Keywords
- alanine transport
- amino acid transport
- brush border transport
- membrane vesicles
- phenylalanine transport
- proline transport
- small intestinal transport
ASJC Scopus subject areas
- Biophysics
- Physiology
- Cell Biology