Bermúdez Moretti M, Correa García S R, Chianelli M S, Ramos E H, Mattoon J R, Batlle A
Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP) (CONICET, F.C.E.y N., UBA), Ciudad Universitaria, Buenos Aires, Argentine.
Int J Biochem Cell Biol. 1995 Feb;27(2):169-73. doi: 10.1016/1357-2725(95)00002-7.
It has been previously reported that 5-aminolevulinic acid (ALA) and 4-aminobutyric acid (GABA) share a common permease in Saccharomyces cerevisiae (Bermúdez Moretti et al., 1993). The aim of the present work was to determine the relationship between the transport of these compounds in isolated cells. Assessment of amino acid incorporation was performed in S. cerevisiae using 14C-ALA or 3H-GABA. Initial rates of ALA incorporation in cells grown in the presence of 5 mM ALA and 5 mM GABA, were three to four times lower than in cells grown without supplements. Kinetic studies indicate that GABA competitively inhibits ALA transport. During the growth phase GABA uptake was also inhibited by 74% and 60% in the presence of ALA and GABA, respectively. These findings indicate that in S. cerevisiae the structurally related compounds, ALA and GABA, may be incorporated into the cells by a common carrier protein. Should this occur in other lukaryotic cells it may explain the neurotoxic effect attributed to ALA in the pathogenesis of acute porphyrias.
先前已有报道称，在酿酒酵母中，5-氨基乙酰丙酸（ALA）和4-氨基丁酸（GABA）共用一种通透酶（贝穆德斯·莫雷蒂等人，1993年）。本研究的目的是确定这些化合物在分离细胞中的转运关系。使用14C-ALA或3H-GABA在酿酒酵母中进行氨基酸掺入评估。在5 mM ALA和5 mM GABA存在下生长的细胞中，ALA掺入的初始速率比未添加补充剂的细胞低三到四倍。动力学研究表明，GABA竞争性抑制ALA转运。在生长阶段，分别在ALA和GABA存在下，GABA摄取也分别被抑制74%和60%。这些发现表明，在酿酒酵母中，结构相关的化合物ALA和GABA可能通过一种共同的载体蛋白进入细胞。如果这种情况发生在其他真核细胞中，这可能解释了急性卟啉病发病机制中ALA所致的神经毒性作用。
