Eipper B A, Mains R E
J Biol Chem. 1979 Oct 25;254(20):10190-9.
Mouse tumor cell beta-lipotropin (beta LPH) and gamma-lipotropin (gamma LPH) were purified from mouse pituitary tumor cell culture medium by ion exchange chromatography and gel filtration. The mouse tumor cell beta LPH was identified by immunoprecipitation with several antisera to beta-endorphin, generation of opioid bioactivity upon brief treatment with trypsin, and its identity with the molecule previously shown to serve as an intermediate in the biosynthesis of beta-endorphin. Mouse tumor cell beta LPH (Mr = 8200 +/- 250) and gamma LPH (Mr = 4600 +/- 200) are significantly smaller than known mammalian beta LPH (Mr = 10,000) and gamma LPH (Mr = 6300) molecules. The beta-endorphin region of mouse tumor cell beta LPH has the same amino acid composition as ovine, bovine, and camel beta-endorphin, and species-specific differences are thus located in the gamma LPH region of the molecule. Mouse tumor cell beta LPH and gamma LPH lack a methionine residue at what had been considered to be a highly conserved site in their beta-melanotropin-like region. A species-specific radioimmunoassay for mouse tumor cell gamma LPH was developed. Rat pituitary beta LPH and gamma LPH were shown to be similar to the corresponding mouse tumor cell molecules in size and lack of methionine in their beta-melanotropin-like segment.
从小鼠垂体肿瘤细胞培养基中通过离子交换色谱法和凝胶过滤法纯化出小鼠肿瘤细胞β-促脂素（β-LPH）和γ-促脂素（γ-LPH）。用几种抗β-内啡肽抗血清进行免疫沉淀、经胰蛋白酶短暂处理后产生阿片样生物活性以及其与先前显示为β-内啡肽生物合成中间体的分子相同，从而鉴定出小鼠肿瘤细胞β-LPH。小鼠肿瘤细胞β-LPH（Mr = 8200 +/- 250）和γ-LPH（Mr = 4600 +/- 200）明显小于已知的哺乳动物β-LPH（Mr = 10,000）和γ-LPH（Mr = 6300）分子。小鼠肿瘤细胞β-LPH的β-内啡肽区域具有与绵羊、牛和骆驼β-内啡肽相同的氨基酸组成，因此物种特异性差异位于该分子的γ-LPH区域。小鼠肿瘤细胞β-LPH和γ-LPH在其β-促黑素样区域中被认为是高度保守的位点处缺乏甲硫氨酸残基。开发了一种针对小鼠肿瘤细胞γ-LPH的物种特异性放射免疫测定法。结果显示，大鼠垂体β-LPH和γ-LPH在大小上与相应的小鼠肿瘤细胞分子相似，并且在其β-促黑素样片段中缺乏甲硫氨酸。
