Hitoshi S, Kusunoki S, Kanazawa I, Tsuji S
Molecular Glycobiology, Frontier Research Program, Institute of Physical and Chemical Research (RIKEN), Saitama, Japan.
J Biol Chem. 1995 Apr 14;270(15):8844-50. doi: 10.1074/jbc.270.15.8844.
Two DNA clones encoding rabbit beta-galactoside alpha 1,2-fucosyltransferase (RFT-I and RFT-II) have been isolated from a rabbit genomic DNA library. The DNA sequences revealed open reading frames coding for 373 (RFT-I) and 354 (RFT-II) amino acids, respectively. The deduced amino acid sequences of RFT-I and RFT-II showed 56% identity with each other, and that of RFT-I showed 80% identity with that of human H blood type alpha 1,2-fucosyltransferase. Northern blot analysis of embryo and adult rabbit tissues revealed that the RFT-I gene was expressed in adult brain, and that the RFT-II gene was expressed in salivary and lactating mammary glands. The identities of these enzymes were confirmed by constructing recombinant fucosyltransferases in which the N-terminal part including the cytoplasmic tail and signal anchor domain was replaced with the immunoglobulin signal peptide sequence. RFT-I expressed in COS-7 cells exhibited similar transferase activity to that of human H blood type alpha 1,2-fucosyltransferase. RFT-II expressed in COS-7 cells showed higher affinity for type 1 (Gal beta 1,3GlcNAc) and type 3 (Gal beta 1,3GalNAc) acceptors than type 2 (Gal beta 1,4GlcNAc) ones, which suggested that RFT-II was a putative secretor-type alpha 1,2-fucosyltransferase.
从兔基因组DNA文库中分离出了两个编码兔β-半乳糖苷α1,2-岩藻糖基转移酶的DNA克隆（RFT-I和RFT-II）。DNA序列显示出分别编码373个氨基酸（RFT-I）和354个氨基酸（RFT-II）的开放阅读框。RFT-I和RFT-II推导的氨基酸序列彼此具有56%的同一性，并且RFT-I的氨基酸序列与人类H血型α1,2-岩藻糖基转移酶的氨基酸序列具有80%的同一性。对胚胎和成年兔组织进行的Northern印迹分析表明，RFT-I基因在成年脑中表达，而RFT-II基因在唾液腺和泌乳乳腺中表达。通过构建重组岩藻糖基转移酶来确认这些酶的同一性，其中包括细胞质尾和信号锚定结构域的N端部分被免疫球蛋白信号肽序列所取代。在COS-7细胞中表达的RFT-I表现出与人类H血型α1,2-岩藻糖基转移酶相似的转移酶活性。在COS-7细胞中表达的RFT-II对1型（Galβ1,3GlcNAc）和3型（Galβ1,3GalNAc）受体的亲和力高于2型（Galβ1,4GlcNAc）受体，这表明RFT-II是一种假定的分泌型α1,2-岩藻糖基转移酶。
