Multiple carriers for dipeptide transport: carrier-mediated transport of glycyl-L-proline in renal BBMV.
Multiple carriers for dipeptide transport: carrier-mediated transport of glycyl-L-proline in renal BBMV.
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用于二肽运输的多个载体：肾 BBMV 中甘氨酰-L-脯氨酸的载体介导的运输。
DOI：
10.1152/ajprenal.1991.261.4.f670
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Peterson,DR
中科院分区：
文献类型：
--
作者：
Skopicki,HA;Fisher,K;Zikos,D;Bloch,R;Flouret,G;Peterson,DR
为了确定多种载体是否负责肾近端小管中甘氨酰-L-脯氨酸（Gly-Pro）的管腔摄取，在刷状缘膜囊泡（BBMV）中测量Gly-[3 H]Pro的转运。Michaelis-Menten动力学的Line-Weaver-Burk分析揭示了两种载体的存在：低亲和力，高容量载体（Km = 1.3 × 10（-2）M; Vmax = 4.6 × 10（-8）mol·mg-1.min-1）和较高亲和力、较低容量载体（Km = 2.7 × 10（-7）M; Vmax = 7.8 × 10（-13）mol·mg-1.min-1）。二肽Gly-Sar、β Ala-His和pyroGlu-His竞争性抑制低亲和力载体。在二肽Gly-Gly或cycloHis-Pro的存在下，在此范围内对Gly-Pro转运的Km或Vmax没有影响。高亲和力载体表现出不同的抑制谱。Gly-Pro转运的竞争性抑制被证明为二肽Gly-Gly和Gly-Sar。然而，上述测试的其他肽都没有改变高亲和力范围内的Gly-Pro转运，包括pyroGlu-His，其由高亲和力载体转运。在低（4 × 10（-8）M）和高（4 × 10（-3）M）浓度下，在存在向内定向H+梯度的情况下刺激Gly-Pro的摄取，但不受向内Na+梯度的影响。此外，在缬氨霉素和外向K+梯度存在下的测量结果强烈表明，在两种浓度下H（+）刺激的摄取是产电的。（250字处删节）
To determine whether multiple carriers are responsible for luminal uptake of glycyl-L-proline (Gly-Pro) in the renal proximal tubule, transport of Gly-[3H]Pro was measured in brush-border membrane vesicles (BBMV). A Line-weaver-Burk analysis of Michaelis-Menten kinetics revealed the presence of two carriers: a lower affinity, higher capacity carrier (Km = 1.3 x 10(-2) M; Vmax = 4.6 x 10(-8) mol.mg-1.min-1) and a higher affinity, lower capacity carrier (Km = 2.7 x 10(-7) M; Vmax = 7.8 x 10(-13) mol.mg-1.min-1). The dipeptides Gly-Sar, beta Ala-His, and pyroGlu-His competitively inhibited the low-affinity carrier. No effect on the Km or Vmax of Gly-Pro transport in this range was seen in the presence of the dipeptides Gly-Gly or cycloHis-Pro. The high-affinity carrier exhibited a different inhibition spectrum. Competitive inhibition of Gly-Pro transport was demonstrated for the dipeptides Gly-Gly and Gly-Sar. However, none of the other peptides tested above altered Gly-Pro transport in the high-affinity range, including pyroGlu-His, which is transported by a high-affinity carrier. At both low (4 x 10(-8) M) and high (4 x 10(-3) M) concentrations, uptake of Gly-Pro was stimulated in the presence of an inwardly directed H+ gradient but was unaffected by the presence of an inward Na+ gradient. In addition, measurements in the presence of valinomycin and an outwardly directed K+ gradient strongly suggest that H(+)-stimulated uptake at both concentrations is electrogenic.(ABSTRACT TRUNCATED AT 250 WORDS)