人胎肝唾液酸转移酶基因的克隆及测序

Cloning and Sequencing of Sialyltransferase Gene from Human Fetal LiverSupported by Special aid of President Fundation of Chinese Academy of Sciences(No.5980601).

根据已克隆的唾液酸转移酶的保守区的序列，以人胎肝ｍＲＮＡ为模板扩增出１５０ｂｐ的片段并测序。其中一个片段（ｓ３８）与已克隆的唾液酸转移酶的活性中心有５７％～９７％的同源性。根据ｓ３８的序列合成寡核苷酸并标记后用作探针筛选人胎肝ｃＤＮＡ文库。从文库中分离了一个编码α２，３唾液酸转移酶的ｃＤＮＡ。该ｃＤＮＡ序列含一个编码３４０个氨基酸的开放读框，推导的氨基酸序列与人颌下腺Ｇａｌβ１，３ＧａｌＮＡｃα２，３唾液酸转移酶相同，与猪颌下腺α２，３唾液酸转移酶有８３２％的同源性。表明从人胎肝ｃＤＮＡ文库中分离的ｃＤＮＡ所编码的蛋白为Ｇａｌβ１，３ＧａｌＮＡｃα２。

Based on the sequences of the highly conserved segments in the previously cloned sialyltransferases,150bp fragments were amplified and sequenced using human fetal liver mRNA as template.One of them (s38) showed 57%～97% identities with the active domains of previously cloned sialyltransferases.Based on the sequence of s38,an oligonucleotide was synthesized and labeled to screen human fetal liver cDNA library.A cDNA encoding α2,3 sialyltransferase has been isolated.The cDNA sequence included an open reading frame coding for 340 amino acids,and the deduced amino acid sequence showed 100% identity with that of human submaxillary gland Galβ1,3GalNAc α2,3 sialyltransferase,83.2% identity with that of pig submaxillary gland α2,3 sialyltransferase.These results suggested the protein encoded by the cDNA from human fetal liver cDNA library was a Galβ1,3GalNAc α2,3 sialyltransferase.