小肠中中性氨基酸转运系统的分析：刷状缘膜囊泡的研究

Analysis of neutral amino acid transport systems in the small intestine: a study of brush border membrane vesicles.

作者信息

Hayashi K, Dojo S, Nakashima K, Nishio E, Kurushima H, Saeki M, Amioka H, Hirata Y, Ohtani H, Hiraoka M

机构信息

First Department of Internal Medicine, Hiroshima University School of Medicine, Japan.

出版信息

Gastroenterol Jpn. 1991 Jun;26(3):287-93. doi: 10.1007/BF02781916.

DOI:10.1007/BF02781916

PMID:1909674

Abstract

Transport of L-proline, L-leucine and L-cysteine was studied in brush border membrane vesicles prepared from guinea pig ileum. Concentrative transport of L-proline, L-leucine and L-cysteine was obtained in the presence of an Na+ gradient from, outside to inside of the vesicles, which indicated contribution of either system A (alanine-preferring) or system ASC (alanine-, serine- and cysteine-preferring) to the transport. When Na+ was replaced by Li+, L-leucine and L-cysteine maintained the same concentrative transport. However, the concentrative transport of L-proline was markedly decreased by Li+ -for-Na+ substitution. Strong exchange properties of L-leucine transport via system L (leucine-preferring) was observed with brush border membrane vesicles, in which preloaded L-methionine could be exchanged with labeled L-leucine added outside the vesicles. These results suggest that the small intestine of the guinea pig possesses classical neutral amino acid transport systems such as systems A, ASC and L.

摘要

在从豚鼠回肠制备的刷状缘膜囊泡中研究了L-脯氨酸、L-亮氨酸和L-半胱氨酸的转运。在囊泡外部到内部存在Na⁺梯度的情况下，获得了L-脯氨酸、L-亮氨酸和L-半胱氨酸的浓缩转运，这表明系统A（偏好丙氨酸）或系统ASC（偏好丙氨酸、丝氨酸和半胱氨酸）对转运有贡献。当Na⁺被Li⁺取代时，L-亮氨酸和L-半胱氨酸保持相同的浓缩转运。然而，Li⁺替代Na⁺后，L-脯氨酸的浓缩转运显著降低。在刷状缘膜囊泡中观察到通过系统L（偏好亮氨酸）转运L-亮氨酸的强交换特性，其中预先加载的L-甲硫氨酸可以与添加在囊泡外部的标记L-亮氨酸进行交换。这些结果表明豚鼠小肠具有经典的中性氨基酸转运系统，如系统A、ASC和L。