Watahiki M, Tanaka M, Masuda N, Sugisaki K, Yamamoto M, Yamakawa M, Nagai J, Nakashima K
Department of Biochemistry, Mie University School of Medicine, Japan.
J Biol Chem. 1989 Apr 5;264(10):5535-9.
The perform of chicken prolactin (PRL) deduced from the cDNA sequence contains a signal peptide of 30 amino acid residues followed by a mature PRL of 199 residues. Chicken PRL shows 77, 68, 67, 58, and 31% identity of amino acid sequence with whale, human, ovine, rat, and salmon PRLs, respectively. Elucidation of the primary structure of avian PRL enabled extended analysis of the specific and conserved amino acid residues and domains of the PRL molecules. The mammalian, teleostean, and avian PRLs share 32 common residues, and these conserved residues are observed to cluster in four distinct domains (PD1 to PD4), corresponding to four of five conserved domains of the growth hormones. Of the 32 residues, 8 residues in the PD2 and PD4 domains, including 4 cysteines, are conserved by other members of the growth hormone family, which indicates that these 8 residues may be essential for common structural features of the gene family. On the other hand, 13 other residues distributed among all four domains are conserved almost exclusively in the PRLs, suggesting that these residues are indispensable for specific binding of the PRLs to their receptors.
从cDNA序列推导的鸡催乳素（PRL）的肽链包含一个由30个氨基酸残基组成的信号肽，其后是一个由199个残基组成的成熟PRL。鸡PRL与鲸、人、羊、大鼠和鲑鱼PRL的氨基酸序列一致性分别为77%、68%、67%、58%和31%。禽类PRL一级结构的阐明使得对PRL分子特定和保守的氨基酸残基及结构域进行扩展分析成为可能。哺乳动物、硬骨鱼类和禽类的PRL共有32个共同残基，并且观察到这些保守残基聚集在四个不同的结构域（PD1至PD4）中，对应于生长激素五个保守结构域中的四个。在这32个残基中，PD2和PD4结构域中的8个残基，包括4个半胱氨酸，为生长激素家族的其他成员所共有，这表明这8个残基可能对于该基因家族的共同结构特征至关重要。另一方面，分布在所有四个结构域中的另外13个残基几乎仅在PRL中保守，这表明这些残基对于PRL与其受体的特异性结合不可或缺。
