Lai Ren, Liu Hen, Lee Wen Hui, Zhang Yun
Department of Animal Toxinology, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223 Peoples Republic of, Yunnan, China.
Peptides. 2002 Mar;23(3):437-42. doi: 10.1016/s0196-9781(01)00642-8.
A novel bombesin-related peptide was isolated from skin secretions of Chinese red belly toad Bombina maxima. Its primary structure was established as pGlu-Lys-Lys-Pro-Pro-Arg-Pro-Pro-Gln-Trp-Ala-Val-Gly-His-Phe-Met-NH(2.) The amino-terminal (N-terminal) 8-residue segment comprising four prolines and three basic residues is extensively different from bombesins from other Bombina species. The peptide was thus named proline rich bombesin (PR-bombesin). PR-bombesin was found to elicit concentration-dependent contractile effects in the rat stomach strip, with both increased potency and intrinsic activity as compared with those of [Leu(13)]bombesin. Analysis of different bombesin cDNA structures revealed that an 8 to 14- nucleotide fragment replacement in the peptide coding region (TGGGGAAT in the cDNAs of multiple bombesin forms from Bombina orientalis and CACCCCGGCCACCC in the cDNA of PR-bombesin) resulted in an unusual Pro-Pro-Arg-Pro-Pro motif in the N-terminal part of PR-bombesin.
从中国红腹铃蟾（Bombina maxima）的皮肤分泌物中分离出一种新型蛙皮素相关肽。其一级结构确定为pGlu-Lys-Lys-Pro-Pro-Arg-Pro-Pro-Gln-Trp-Ala-Val-Gly-His-Phe-Met-NH₂。包含四个脯氨酸和三个碱性残基的氨基末端（N端）8个残基片段与其他铃蟾属物种的蛙皮素存在广泛差异。因此，该肽被命名为富含脯氨酸的蛙皮素（PR-蛙皮素）。研究发现，与[Leu(13)]蛙皮素相比，PR-蛙皮素在大鼠胃条上能引发浓度依赖性收缩效应，且效力和内在活性均有所增加。对不同蛙皮素cDNA结构的分析表明，肽编码区中8至14个核苷酸片段的替换（东方铃蟾多种蛙皮素形式的cDNA中的TGGGGAAT以及PR-蛙皮素cDNA中的CACCCCGGCCACCC）导致PR-蛙皮素N端出现异常的Pro-Pro-Arg-Pro-Pro基序。
