Key result
Application of the acidic calcium-binding protein S100B causes Ca(2+)-dependent inhibition of expressed hEAG1 channels and shares the same binding sites with calmodulin.
S100B acts as a potential alternative calcium sensor for hEAG1 potassium channels, mediating Ca2+-dependent inhibition.
No immediate clinical implications; leaves open S100B as alternative Ca2+ sensor for hEAG1, requiring in vivo validation.
Voltage-dependent human ether à go-go (hEAG1) potassium channels are implicated in neuronal signaling as well as in cancer cell proliferation. Unique sensitivity of the channel to intracellular Ca(2+) is mediated by calmodulin (CaM) binding to the intracellular N- and C-termini of the channel. Here we show that application of the acidic calcium-binding protein S100B to inside-out patches of Xenopus oocytes causes Ca(2+)-dependent inhibition of expressed hEAG1 channels. Protein pull-down assays and fluorescence correlation spectroscopy (FCS) revealed that S100B binds to hEAG1 and shares the same binding sites with CaM. Thus, S100B is a potential alternative calcium sensor for hEAG1 potassium channels.
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Sahoo et al. (2010) studied this question. S100B was evaluated on Ca(2+)-dependent inhibition of expressed hEAG1 channels and binding to hEAG1. Application of the acidic calcium-binding protein S100B causes Ca(2+)-dependent inhibition of expressed hEAG1 channels and shares the same binding sites with calmodulin.
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