Wodnar-Filipowicz A, Gubler U, Furuichi Y, Richardson M, Nowoswiat E F, Poonian M S, Horecker B L
Proc Natl Acad Sci U S A. 1984 Apr;81(8):2295-7. doi: 10.1073/pnas.81.8.2295.
Molecular cloning of a cDNA has established the sequence of the translated portion of the mRNA for rat spleen thymosin beta 4. The presence of a methionyl initiator codon immediately preceding the codon for the first seryl residue of mature thymosin beta 4 is consistent with previous results indicating the absence of a signal peptide in the product translated in vitro from rat spleen mRNA. The cDNA sequence analysis also established the presence of two terminator codons immediately following the codon for the COOH-terminal seryl residue. Thymosin beta 4 is thus synthesized as a 5100-dalton peptide containing 44 amino acid residues. Removal of the initiator methionyl residue and acetylation of the NH2-terminal serine residue would yield mature thymosin beta 4 containing 43 amino acids. The absence of a signal peptide makes it unlikely that thymosin beta 4 is a secreted peptide.
通过对一个cDNA进行分子克隆，已确定了大鼠脾脏胸腺素β4的mRNA翻译部分的序列。在成熟胸腺素β4的第一个丝氨酰残基的密码子之前紧邻着一个甲硫氨酰起始密码子，这与之前的结果一致，即从大鼠脾脏mRNA体外翻译的产物中不存在信号肽。cDNA序列分析还确定在COOH末端丝氨酰残基的密码子之后紧接着有两个终止密码子。因此，胸腺素β4是以一个含有44个氨基酸残基的5100道尔顿的肽形式合成的。去除起始甲硫氨酰残基并将NH2末端丝氨酸残基乙酰化，将产生含有43个氨基酸的成熟胸腺素β4。不存在信号肽表明胸腺素β4不太可能是一种分泌肽。
