Furriols M, Chillarón J, Mora C, Castelló A, Bertran J, Camps M, Testar X, Vilaró S, Zorzano A, Palacín M
Departament de Bioquímica i Fisiologia, Facultat de Biologia, Universitat de Barcelona, Spain.
J Biol Chem. 1993 Dec 25;268(36):27060-8.
We have recently isolated a renal cDNA clone (rBAT) that induces amino acid transport in oocytes either as a component or as a specific activator of a system bo,(+)-like transporter. (Bertran, J., Werner, A., Moore, M. L., Stange, G., Markovich, D., Biber, J., Testar, X., Zorzano, A., Palacín, M., and Murer, H. (1992) Proc. Natl. Acad. Sci. U. S. A. 89, 5601-5605. In order to obtain additional information on the rBAT protein, we have investigated the cellular localization of rBAT and its expression during development in rat kidney. A polyclonal antibody raised against rBAT recognizes a specific protein band of approximately 90 kDa, which is highly enriched in rat renal brush border membranes. Immunofluorescence and immunoelectron microscopy studies demonstrated that rBAT is expressed in the microvilli domain of S3 epithelial cells (i.e. straight tubules). The onset of rBAT mRNA expression in kidney was detected during late fetal life. In keeping with this, induction in oocytes of L-cystine uptake due to fetal rBAT-related mRNA was approximately 10% of the induction obtained with rBAT-related mRNA from adult kidneys. rBAT mRNA levels were low in early postnatal life, and only at the end of lactation did they increase steeply, attaining approximately 50% of adult values after weaning. rBAT protein was undetectable in total membrane preparations of kidneys from fetuses and early neonates, weakly detected during lactation, and represented < 15% of adult values after weaning. The postnatal expression of rBAT and its specific location in the microvilli of epithelial cells from the S3 segment of the proximal tubule coincide with postnatal maturation of cystine resorption and with the site of high affinity resorption of cysteine in kidney. This is consistent with the involvement of rBAT in a b(o,+)-like high-affinity resorption system for cysteine in the proximal straight tubule of the nephron.
我们最近分离出一个肾脏cDNA克隆（rBAT），它作为系统bo，（+）样转运体的一个组成部分或特定激活剂，可诱导卵母细胞中的氨基酸转运。（Bertran，J.，Werner，A.，Moore，M.L.，Stange，G.，Markovich，D.，Biber，J.，Testar，X.，Zorzano，A.，Palacín，M.，以及Murer，H.（1992年）美国国家科学院院刊89，5601 - 5605页。为了获得有关rBAT蛋白的更多信息，我们研究了rBAT在大鼠肾脏发育过程中的细胞定位及其表达情况。针对rBAT产生的多克隆抗体识别出一条约90 kDa的特异性蛋白条带，该条带在大鼠肾刷状缘膜中高度富集。免疫荧光和免疫电子显微镜研究表明，rBAT在S3上皮细胞（即直小管）的微绒毛区域表达。在胎儿晚期检测到肾脏中rBAT mRNA表达的起始。与此一致的是，由于胎儿rBAT相关mRNA导致的L - 胱氨酸摄取在卵母细胞中的诱导率约为来自成年肾脏的rBAT相关mRNA诱导率的10%。rBAT mRNA水平在出生后早期较低，仅在哺乳期结束时急剧增加，断奶后达到成年值的约50%。在胎儿和早期新生儿肾脏的总膜制剂中未检测到rBAT蛋白，哺乳期微弱检测到，断奶后占成年值不到15%。rBAT的出生后表达及其在近端小管S3段上皮细胞微绒毛中的特定位置与胱氨酸重吸收的出生后成熟以及肾脏中半胱氨酸高亲和力重吸收的部位一致。这与rBAT参与肾单位近端直小管中半胱氨酸的b（o，+）样高亲和力重吸收系统一致。
