Jin W, Lu Z
Department of Physiology, University of Pennsylvania, Philadelphia 19104, USA.
Biochemistry. 1999 Oct 26;38(43):14286-93. doi: 10.1021/bi991205r.
Tertiapin (TPN), a small protein derived from honey bee venom, inhibits the GIRK1/4 and ROMK1 channels with nanomolar affinities. Methionine residue 13 in TPN interacts with residue F148 in the channel, located just outside of the narrow region of the ROMK1 pore. The methionine residue in TPN can be oxidized by air, which significantly hinders TPN binding to the channels. To overcome the reduction in TPN affinity due to oxidation of M13, we replaced M13 in TPN with fourteen different residues. Out of the fourteen derivatives, only the one in which M13 was replaced by glutamine, TPNQ, binds to the channel with a Ki value very similar to that of native TPN. Since TPNQ is stable and functionally resembles native TPN, it will be a very useful molecular probe for studying the inward-rectifier K+ channels.
蜂毒明肽（TPN）是一种源自蜜蜂毒液的小蛋白质，它以纳摩尔亲和力抑制GIRK1/4和ROMK1通道。TPN中的甲硫氨酸残基13与通道中的F148残基相互作用，该残基位于ROMK1孔的狭窄区域外侧。TPN中的甲硫氨酸残基可被空气氧化，这显著阻碍了TPN与通道的结合。为了克服由于M13氧化导致的TPN亲和力降低，我们用14种不同的残基替换了TPN中的M13。在这14种衍生物中，只有M13被谷氨酰胺取代的那种，即TPNQ，以与天然TPN非常相似的Ki值与通道结合。由于TPNQ稳定且功能上类似于天然TPN，它将成为研究内向整流钾通道的非常有用的分子探针。
