Russo D, Wu X, Redman C M, Lee S
Lindsley F. Kimball Research Institute, The New York Blood Center, New York, New York 10021, USA.
Blood. 2000 Jul 1;96(1):340-6.
The Kell blood group protein is a zinc endopeptidase that yields endothelin-3, a potent bioactive peptide, by cleavage of big endothelin-3, a larger intermediate precursor. On red cells, Kell protein is linked by a single disulfide bond to XK, a protein that traverses the membrane 10 times and whose absence, as occurs in the McLeod phenotype, is associated with a set of clinical symptoms that include nerve and muscle disorders and red cell acanthocytosis. Previous studies indicated that Kell is primarily expressed in erythroid tissues, whereas XK has a wider tissue distribution. The tissue distribution of Kell protein has been further investigated by Northern blot analysis, PCR-screening of tissue complementary DNAs (cDNAs), and Western immunoblots. Screening of an RNA dot-blot panel confirmed that Kell is primarily expressed in erythroid tissues but is also expressed in a near equal amount in testis, with weaker expression in a large number of other tissues. PCR-screening of cDNAs from different tissues and DNA sequencing of the products gave similar results. In 2 of the nonerythroid tissues tested, testis and skeletal muscle, Kell protein was detected by Western immunoblotting. In skeletal muscle, isolation of XK with a specific antibody coisolated Kell protein. These studies demonstrate that Kell is expressed in both erythroid and nonerythroid tissues and is associated with XK.
凯尔血型蛋白是一种锌内肽酶，它通过切割大内皮素-3（一种更大的中间前体）产生内皮素-3（一种强效生物活性肽）。在红细胞上，凯尔蛋白通过一个二硫键与XK相连，XK是一种跨膜10次的蛋白质，其缺失（如在麦克劳德表型中出现的情况）与一系列临床症状相关，包括神经和肌肉疾病以及红细胞棘形细胞增多症。先前的研究表明，凯尔蛋白主要在红系组织中表达，而XK具有更广泛的组织分布。通过Northern印迹分析、组织互补DNA（cDNA）的PCR筛选以及Western免疫印迹法对凯尔蛋白的组织分布进行了进一步研究。对RNA点杂交板的筛选证实，凯尔蛋白主要在红系组织中表达，但在睾丸中的表达量也几乎相同，在大量其他组织中的表达较弱。对来自不同组织的cDNA进行PCR筛选以及对产物进行DNA测序得到了类似的结果。在测试的非红系组织中的2种组织，即睾丸和骨骼肌中，通过Western免疫印迹法检测到了凯尔蛋白。在骨骼肌中，用特异性抗体分离XK时同时分离出了凯尔蛋白。这些研究表明，凯尔蛋白在红系和非红系组织中均有表达，并且与XK相关。
