Suda K, Smith D M, Ghatei M A, Bloom S R
Department of Medicine, Royal Postgraduate Medical School, Hammersmith Hospital, London, UK.
Neurosci Lett. 1992 Mar 16;137(1):19-23. doi: 10.1016/0304-3940(92)90288-i.
We have compared the binding of [125I]vasoactive intestinal polypeptide (VIP) to human brain membranes with that of [125I]PACAP27. [125I]VIP was displaced by PACAP27, VIP and two synthetic peptides, peptide-1 (N-terminal PACAP27/C-terminal VIP) and peptide-2 (N-terminal VIP/C-terminal PACAP27), but the IC50 of PACAP27 and peptide-1 were 10-20 times lower than those of VIP and peptide-2. [125I]PACAP27 was readily displaced by PACAP27 and peptide-1, with an IC50 of less than 1 nM, but poorly by VIP and peptide-2. Chemical cross-linking revealed that both labels were bound to polypeptides of Mr 66,000 and Mr 50,000. The results indicate that in human brain membranes both binding sites have a higher affinity to the N-terminal sequence of PACAP27, and VIP binding sites prefer PACAP27 to VIP itself.
我们已将[125I]血管活性肠肽（VIP）与人脑膜的结合与[125I]垂体腺苷酸环化酶激活肽27（PACAP27）的结合进行了比较。[125I]VIP被PACAP27、VIP以及两种合成肽——肽-1（N端为PACAP27/C端为VIP）和肽-2（N端为VIP/C端为PACAP27）取代，但PACAP27和肽-1的半数抑制浓度（IC50）比VIP和肽-2低10至20倍。[125I]PACAP27很容易被PACAP27和肽-1取代，IC50小于1 nM，但被VIP和肽-2取代的程度较差。化学交联显示，两种标记物均与分子量为66,000和50,000的多肽结合。结果表明，在人脑膜中，两个结合位点对PACAP27的N端序列具有更高的亲和力，并且VIP结合位点对PACAP27的偏好高于对VIP自身的偏好。
