Hayashi K, Agata K, Mochii M, Yasugi S, Eguchi G, Mizuno T
Zoological Institute, Faculty of Science, University of Tokyo.
J Biochem. 1988 Feb;103(2):290-6. doi: 10.1093/oxfordjournals.jbchem.a122263.
Embryonic chicken pepsinogen is an aspartyl proteinase that is specifically secreted during the embryonic period in the chicken proventriculus (glandular stomach). To learn the phylogeny of this pepsinogen, we isolated a cDNA clone by screening a lambda gt11 library of embryonic proventricular cDNAs with an antiserum to the embryonic chicken pepsinogen. We obtained a 200-base pair cDNA clone which encoded 18 amino acids that had high sequence homology with the carboxyl termini of other pepsinogens. Northern blot analysis revealed that this cDNA clone hybridized to a mRNA of 1,600 bases in the embryonic proventriculus but not to the mRNA in the adult proventriculus. The almost complete nucleotide sequence of embryonic chicken pepsinogen-cDNA was determined by sequencing longer cDNAs obtained by screening the same library with the 200-base pair cDNA and primer extension with a synthetic primer. The cDNA consisted of 1,281 nucleotides and encoded 383 amino acids for prepepsinogen. The predicted amino acid sequence was compared with the sequences of other aspartyl proteinases: pepsinogen A of human, monkey, pig, and chicken, progastricsin of monkey and rat, and bovine prochymosin. The phylogenetic tree constructed for them indicates the possibility that embryonic chicken pepsinogen diverged from prochymosin, after prochymosin and pepsinogen A had diverged from each other.
胚胎期鸡胃蛋白酶原是一种天冬氨酸蛋白酶，在鸡前胃（腺胃）胚胎期特异性分泌。为了解这种胃蛋白酶原的系统发生，我们用抗胚胎期鸡胃蛋白酶原的抗血清筛选胚胎前胃cDNA的λgt11文库，分离出一个cDNA克隆。我们获得了一个200个碱基对的cDNA克隆，它编码18个氨基酸，与其他胃蛋白酶原的羧基末端有高度的序列同源性。Northern印迹分析表明，这个cDNA克隆与胚胎前胃中1600个碱基的mRNA杂交，但不与成年前胃中的mRNA杂交。通过用200个碱基对的cDNA筛选同一文库并使用合成引物进行引物延伸，测定了胚胎期鸡胃蛋白酶原-cDNA的几乎完整的核苷酸序列。该cDNA由1281个核苷酸组成，编码前胃蛋白酶原的383个氨基酸。将预测的氨基酸序列与其他天冬氨酸蛋白酶的序列进行比较：人、猴、猪和鸡的胃蛋白酶原A，猴和大鼠的前胃泌素，以及牛凝乳酶原。为它们构建的系统发生树表明，胚胎期鸡胃蛋白酶原可能在凝乳酶原和胃蛋白酶原A彼此分化后从凝乳酶原分化而来。
