Chatterjee Abhijit, Shen San-Tai, Yu John Yuh-Lin
Endocrinology Laboratory, Institute of Zoology, Academia Sinica, 128 Academia Road, Section II, Taipei 115, Taiwan, ROC.
Gen Comp Endocrinol. 2005 Sep 15;143(3):278-86. doi: 10.1016/j.ygcen.2005.04.004.
The cDNAs encoding beta-subunits of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) have been cloned from the pituitary of snakehead fish, Channa maculata, and the three-dimensional structural models of the encoded FSH and LH were investigated. The cloned cDNAs, including 5'-untranslated region (UTR), open-reading frame, and 3'-UTR followed by a poly(A) tail, were obtained by reverse transcription-polymerase chain reaction and rapid amplification of cDNA end methods. The open-reading frames of FSH-beta cDNA encodes a 120-amino acid protein with a signal peptide of 18 amino acids and a mature protein of 102 amino acids; while LH-beta cDNA encodes a 140-amino acid protein with a signal peptide of 33 amino acids and a mature protein of 115 amino acids. The amino acid sequence identities of snakehead fish FSH-beta and LH-beta in comparison with other fish are 27.8-81.9% and 45.2-88.8%, respectively; while in comparison with tetrapods are 26.2-28.9% and 37.5-51.2%, respectively. Both FSH-beta and LH-beta of snakehead fish resemble most to those of Perciformes, implying their closer phylogenetic relationship. All 12 cysteine residues are conserved in snakehead fish LH-beta; while 11 cysteine residues are conserved in its FSH-beta. The third cysteine is absent in snakehead fish FSH-beta; instead, a positionally shifted cysteine residue is present at the N-terminus, as found in some phylogenetic related fish. The structure models of snakehead fish FSH and LH, constructed by using the crystal structures of human FSH and human chorionic gonadotropin as respective template, showed that the positionally shifted N-terminal cysteine residue of snakehead fish FSH-beta likely can substitute the third cysteine to form a disulfide bond with the 12th cysteine.
从斑鳢垂体中克隆出了编码促卵泡激素（FSH）和促黄体生成素（LH）β亚基的cDNA，并对编码的FSH和LH的三维结构模型进行了研究。通过逆转录-聚合酶链反应和cDNA末端快速扩增方法获得了克隆的cDNA，包括5'-非翻译区（UTR）、开放阅读框和带有poly(A)尾的3'-UTR。FSH-β cDNA的开放阅读框编码一个120个氨基酸的蛋白质，带有一个18个氨基酸的信号肽和一个102个氨基酸的成熟蛋白；而LH-β cDNA编码一个140个氨基酸的蛋白质，带有一个33个氨基酸的信号肽和一个115个氨基酸的成熟蛋白。斑鳢FSH-β和LH-β与其他鱼类相比，氨基酸序列同一性分别为27.8-81.9%和45.2-88.8%；与四足动物相比，分别为26.2-28.9%和37.5-51.2%。斑鳢的FSH-β和LH-β与鲈形目鱼类的最为相似，这意味着它们有更近的系统发育关系。斑鳢LH-β中的所有12个半胱氨酸残基都是保守的；而其FSH-β中有11个半胱氨酸残基是保守的。斑鳢FSH-β中没有第三个半胱氨酸；相反，在一些系统发育相关的鱼类中发现，在N端有一个位置偏移的半胱氨酸残基。以人FSH和人绒毛膜促性腺激素的晶体结构为各自模板构建的斑鳢FSH和LH的结构模型表明，斑鳢FSH-β中位置偏移的N端半胱氨酸残基可能可以替代第三个半胱氨酸，与第12个半胱氨酸形成二硫键。
