期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 97, 期 9, 页码 4814-4819出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.97.9.4814
关键词
-
资金
- NIDDK NIH HHS [DK41415] Funding Source: Medline
The extracellular calcium (Ca-o(2+))-sensing receptor (CaR) recognizes and responds to (i.e., senses) Ca-o(2+) as its principal physiological ligand, In the present studies, we document that the CaR is activated not only by extracellular calcium ions but also by amino acids, establishing its capacity to sense nutrients of two totally different classes, L-Amino acids, especially aromatic amino acids, including L-phenylalanine and L-tryptophan, stereoselectively mobilized Ca2+ ions in the presence of the CaR agonists, Ca-o(2+), gadolinium (Gd-o(3+)), and spermine in fura-2-loaded human embryonic kidney (HEK-293) cells stably transfected with the human CaR. L-amino acid-dependent effects were observed above, but not below, a threshold level of Ca-o(2+) of approximately 1.0 mM. L-Amino acids, particularly aromatic amino acids, also stereoselectively enhanced the sensitivity of the CaR to its agonists, Ca-o(2+) and spermine. Branched-chain amino acids were almost inactive, and charged amino acids, including arginine and lysine, were much less effective than aromatic and other amino acids. L-amino acid mixtures emulating the amino acid composition of fasting human plasma reproduced the effects of high concentrations of individual L-amino acids on Ca2+ mobilization and enhanced the sensitivity of the CaR to Ca-o(2+). The data presented herein identify the CaR as a molecular target for aromatic and other L-amino acids. Thus, the CaR can integrate signals arising from distinct classes of nutrients: mineral ions and amino acids. The actions of L-amino acids on the CaR may provide explanations for several long recognized but poorly understood actions of dietary protein on calcium metabolism.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据