Watanabe K, Yamaguchi Y
Burnham Institute, California 92037, USA.
J Biol Chem. 1996 Sep 20;271(38):22945-8. doi: 10.1074/jbc.271.38.22945.
To identify the putative mammalian hyaluronan synthase, we cloned a human cDNA that is related to the Streptococcus hyaluronan synthase (HasA) and the Xenopus developmental protein DG42 which has been shown to have chitin synthase activity. The cDNA, for which we propose the name Has2, encodes a novel protein with a predicted molecular mass of 63.6 kDa. Has2 shows 55% amino acid identity with Xenopus DG42 and 52% identity with the mouse HAS protein, another putative hyaluronan synthase recently reported by Itano and Kimata (Itano, N., and Kimata, K. (1996) J. Biol. Chem. 271, 9875-9878). The deduced primary structure revealed the presence of several hydrophobic stretches which can form multiple transmembrane domains. It also demonstrated the complete conservation of amino acid residues that are known to be critical for N-acetylglucosaminyltransferase activity of yeast chitin synthase. When the Has2 cDNA was transfected into human 293 and Chinese hamster ovary cells, the production of hyaluronan in the transfected cells increased up to 34- and 9-fold, respectively. Strong expression of Has2 mRNA was observed in exponentially proliferating human IMR-90 fibroblasts but not in growth-arrested IMR-90 cells. These results suggest that the Has2 protein is a crucial component of the human hyaluronan synthase system.
为了鉴定假定的哺乳动物透明质酸合酶，我们克隆了一个人类cDNA，它与链球菌透明质酸合酶（HasA）以及非洲爪蟾发育蛋白DG42相关，DG42已被证明具有几丁质合酶活性。我们将该cDNA命名为Has2，它编码一种预测分子量为63.6 kDa的新型蛋白质。Has2与非洲爪蟾DG42的氨基酸同一性为55%，与小鼠HAS蛋白（Itano, N.和Kimata, K.（1996年）《生物化学杂志》271卷，9875 - 9878页最近报道的另一种假定的透明质酸合酶）的同一性为52%。推导的一级结构显示存在几个疏水片段，可形成多个跨膜结构域。它还表明，已知对酵母几丁质合酶的N - 乙酰葡糖胺基转移酶活性至关重要的氨基酸残基完全保守。当将Has2 cDNA转染到人293细胞和中国仓鼠卵巢细胞中时，转染细胞中透明质酸的产生分别增加了34倍和9倍。在指数增殖的人IMR - 90成纤维细胞中观察到Has2 mRNA的强表达，但在生长停滞的IMR - 90细胞中未观察到。这些结果表明，Has2蛋白是人类透明质酸合酶系统的关键组成部分。
