组织型纤溶酶原激活剂（t－PA）cDNA序列的测定

已经从ｍｅｌａｎｏｍａ细胞系中成功地获得了人组织型纤溶酶原激活剂（ｔ－ＰＡ）ｃＤＮＡ，在此基础上用双脱氧终止法测定了ｔ－ＰＡｃＤＮＡ编码区全序列及３′非编码区部分序列，并发现与Ｐｅｎｎｉｃａ等发表的ｔ－ＰＡｃＤＮＡ序列相比，有两处差异，其一是第１７２５位核苷酸残基为Ｃ而非Ａ，并使此处序列与Ｐｅｎｎｉｃａ序列相比新产生一个ＳｔｙＩ切点，但由于差异发生在密码子第三位，没有引起编码的氨基酸变化；其二是第１７７７位核苷酸残基（终止密码子后第４位核苷酸残基）为Ｔ而非Ｇ，使与终止密码子相隔３个核苷酸残基处产生了一个新的ＴＧＡ，与Ｐｅｎｎｉｃａ序列相比此处的ＢｓｔＮＩ切点也消失了。

Sequence Analysis Of the Complementary DNA(cDNA)of Tissue-Type Plasminogen Activator(t-PA)

The complementary DNA of tissue-type plasminogen activator (t-PA) had been cloned in this laboratary. In this paper, the cDNA of t-PA was further sequenced , and two differences in nucleotides were found as compared with the sequence published by Pennica et al. One of the differences occurs at nucleotide number 1725 where C replaces A, and thus, produces a new Sty I restriction site. Another difference occurs at nucleotide number 1777, 4 nucleotides downstream of the stop codon TGA, i. e. , T replaces G, as compared with the sequence published by Pennica et al. The change eliminates the BstN I restriction site in our preduct.