Heinig J A, Keeley F W, Robson P, Sower S A, Youson J H
Department of Anatomy and Cell Biology, University of Toronto, Ontario, Canada.
Gen Comp Endocrinol. 1995 Aug;99(2):137-44. doi: 10.1006/gcen.1995.1094.
A proopiomelanocortin (POMC)-like hormone has been cloned and sequenced from a pituitary cDNA library of upstream migrant (prespawning) sea lamprey, Petromyzon marinus. The clone, designated LPP-1, consisted of 986 nucleotides, with an open reading frame of 277 amino acids, including a signal peptide of 22 amino acids. Like POMCs from more recently evolved vertebrates, lamprey POMC contained domains which corresponded to alpha-MSH, ACTH, and beta-endorphin. However, sequences corresponding to gamma- and beta-MSH are absent or likely nonfunctional, respectively, in this cDNA. Northern blot analyses showed low but detectable expression levels of LPP-1 in larvae and strong expression in parasitic adults and prespawning animals. These observations indicate that a recognizable POMC, distinct from proenkephalin, has an ancient lineage within subphylum Vertebrata, likely dating back to the last common ancestor of the lamprey and gnathostome lines.
从溯河洄游（产卵前）海七鳃鳗（Petromyzon marinus）的垂体cDNA文库中克隆并测序了一种阿片促黑皮质素原（POMC）样激素。该克隆体命名为LPP-1，由986个核苷酸组成，开放阅读框为277个氨基酸，包括一个22个氨基酸的信号肽。与新近进化的脊椎动物的POMC一样，七鳃鳗POMC含有与α-促黑素细胞激素（α-MSH）、促肾上腺皮质激素（ACTH）和β-内啡肽相对应的结构域。然而，在该cDNA中，与γ-促黑素细胞激素和β-促黑素细胞激素相对应的序列分别不存在或可能无功能。Northern印迹分析表明，LPP-1在幼体中的表达水平较低但可检测到，而在寄生成体和产卵前动物中表达强烈。这些观察结果表明，一种与脑啡肽原不同的可识别的POMC在脊椎动物亚门中具有古老的谱系，可能可追溯到七鳃鳗和有颌类动物谱系的最后一个共同祖先。
