Okada T, Kawazoe I, Kimura S, Sasamoto Y, Aida K, Kawauchi H
Central Research Institute, Maruha Corporation, Ibaraki, Japan.
Int J Pept Protein Res. 1994 Jan;43(1):69-80. doi: 10.1111/j.1399-3011.1994.tb00377.x.
The duality of teleost pituitary gonadotropins was established in an advanced marine fish, the tuna (Thunnus obesus). Two different molecular forms of gonadotropins, designated tGTH I and tGTH II, were isolated from an alcoholic extract of pituitary glands following ion-exchange chromatography and reversed-phase HPLC. Both tGTH I and tGTH II stimulated estradiol-17 beta and testosterone production in tuna ovarian follicles in vitro, although responses to tGTH II were significantly greater than those to tGTH I. Each gonadotropin consisted of alpha- and beta-subunits. tGTH I was stable in acidic conditions, whereas tGTH II dissociated into two subunits after acid treatment. Alpha subunits of tGTH I and tGTH II had identical amino acid sequences of 94 amino acid residues. The tGTH I beta and tGTH II beta consisted of 102 and 115 amino acid residues, respectively, and showed 35% sequence identity. tGTH I beta is structurally more similar to salmon GTH I beta than to salmon GTH II beta, whereas tGTH II beta is more similar to salmon GTH II beta. Thus it is evident that the tuna pituitary gland produces two chemically distinct gonadotropins.
硬骨鱼垂体促性腺激素的二元性是在一种高级海鱼金枪鱼（Thunnus obesus）中确定的。通过离子交换色谱和反相高效液相色谱法，从垂体的乙醇提取物中分离出两种不同分子形式的促性腺激素，分别命名为tGTH I和tGTH II。体外实验中，tGTH I和tGTH II均能刺激金枪鱼卵巢卵泡产生雌二醇-17β和睾酮，不过tGTH II的刺激反应显著大于tGTH I。每种促性腺激素都由α亚基和β亚基组成。tGTH I在酸性条件下稳定，而tGTH II经酸处理后会解离成两个亚基。tGTH I和tGTH II的α亚基具有相同的94个氨基酸残基的氨基酸序列。tGTH Iβ由102个氨基酸残基组成，tGTH IIβ由115个氨基酸残基组成，二者的序列一致性为35%。tGTH Iβ在结构上与鲑鱼GTH Iβ的相似性高于与鲑鱼GTH IIβ的相似性，而tGTH IIβ与鲑鱼GTH IIβ更相似。因此，很明显金枪鱼垂体产生两种化学性质不同的促性腺激素。
