Sato T, Aoki N, Matsuda T, Furukawa K
Department of Biosignal Research, Tokyo Metropolitan Institute of Gerontology, Japan.
Biochem Biophys Res Commun. 1998 Mar 27;244(3):637-41. doi: 10.1006/bbrc.1998.8327.
We isolated a human cDNA clone encoding beta-1,4-galactosyltransferase (beta-1,4-GalT IV) which shares 37% identity with previously characterized mammalian beta-1,4-GalT (beta-1,4-GalT I). By transfection of the full length cDNA into Sf-9 cells and assay of the cell homogenates, higher beta-1,4-GalT activity toward GlcNAc beta-S-pNP was obtained, and its activity was modulated with alpha-lactalbumin, while no lactose synthetase activity was detected in the presence of alpha-lactalbumin. Northern blot analysis using total and poly (A)+ RNA preparations revealed that the expression level of beta-1,4-GalT IV transcript is low and relatively constant while that of beta-1,4-GalT I transcript is dramatically increased in the mouse mammary gland during lactation. These results indicate that beta-1,4-GalT IV can interact with alpha-lactalbumin but has no lactose synthetase activity.
我们分离出了一个编码β-1,4-半乳糖基转移酶（β-1,4-GalT IV）的人类cDNA克隆，它与先前鉴定的哺乳动物β-1,4-半乳糖基转移酶（β-1,4-GalT I）有37%的同源性。通过将全长cDNA转染到Sf-9细胞中并检测细胞匀浆，获得了对GlcNAcβ-S-pNP更高的β-1,4-GalT活性，其活性受α-乳白蛋白调节，而在α-乳白蛋白存在的情况下未检测到乳糖合成酶活性。使用总RNA和聚腺苷酸加尾（poly(A)+）RNA制剂进行的Northern印迹分析表明，β-1,4-GalT IV转录本的表达水平较低且相对恒定，而β-1,4-GalT I转录本在小鼠乳腺泌乳期间显著增加。这些结果表明，β-1,4-GalT IV可以与α-乳白蛋白相互作用，但没有乳糖合成酶活性。
