CHARACTERISTICS OF CYSTINE COUNTER-TRANSPORT IN NORMAL AND CYSTINOTIC LYSOSOME-RICH LEUKOCYTE GRANULAR FRACTIONS
CHARACTERISTICS OF CYSTINE COUNTER-TRANSPORT IN NORMAL AND CYSTINOTIC LYSOSOME-RICH LEUKOCYTE GRANULAR FRACTIONS
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DOI：
10.1042/bj2160393
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发表时间：
1983-01-01
影响因子：
4.1
通讯作者：
SCHULMAN, JD
中科院分区：
文献类型：
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作者：
GAHL, WA;TIETZE, F;SCHULMAN, JD
正常的白细胞溶酶体富含颗粒组分表现出胱氨酸的反向转运，证实了胱氨酸通过溶酶体膜的转运是由载体介导的。胱氨酸转运的反式激活依赖于温度，但相对独立于磷酸盐缓冲液中的外部Na+或K+浓度。反向转运，测量为摄取外源[~3H]胱氨酸，随着溶酶体内胱氨酸含量的增加而增加，直到.apprx。半胱氨酸/U的己糖胺酶活力为3nmoL。溶酶体外培养上清液中加入未标记半胱氨酸后，[~3H]半胱氨酸进入溶酶体的量减少。溶酶体的半胱氨酸反向转运对L异构体具有立体特异性。半胱硫氨酸、半胱胺和半胱胺-半胱氨酸混合二硫化物提供了共享溶酶体胱氨酸转运系统的证据，尽管其活性低于胱氨酸。其他被测试的氨基酸，包括精氨酸、谷氨酸和同型半胱氨酸，在这个系统中都是不活跃的。来自8个不同的膀胱虫病患者的9种富含白细胞溶酶体的制剂几乎没有显示出胱氨酸的反向转运，这一结论表明，在膀胱虫病患者中，载体介导的胱氨酸转运系统是功能失调的。
Normal leukocyte lysosome-rich granular fractions exhibited counter-transport of cystine, confirming that cystine transport across the lysosomal membrane is carrier-mediated. The trans-activation of cystine transport was temperature-dependent but relatively independent of the external Na+ or K+ concentration in phosphate buffer. Counter-transport, measured as uptake of exogenous [3H]cystine, increased with increasing intralysosomal cystine content up to .apprx. 3 nmol of half-cystine/U of hexosamindase activity. The amount of [3H]cystine entering lysosomes loaded with unlabeled cystine decreased when unlabeled cystine was added to the extralysosomal medium. Lysosomal cystine counter-transport was stereospecific for the L-isomer. Cystathionine, cystamine and cysteamine-cystine mixed disulfide gave evidence of sharing the lysosomal cystine-transport system, although at lower activity than cystine. Other tested amino acids, including arginine, glutamate and homocystine, were inactive in this system. Nine leukocyte lysosome-rich preparations from 8 different cystinotic patients displayed virtually no counter-transport of cystine, conclusively establishing that a carrier-mediated system for cystine transport is dysfunctional in cystinotic lysosomes.