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J Gen Physiol 2018 May 07;1505:683-696. doi: 10.1085/jgp.201812064.
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Dimerization of the voltage-sensing phosphatase controls its voltage-sensing and catalytic activity.

Rayaprolu V , Royal P , Stengel K , Sandoz G , Kohout SC .

Multimerization is a key characteristic of most voltage-sensing proteins. The main exception was thought to be the Ciona intestinalis voltage-sensing phosphatase (Ci-VSP). In this study, we show that multimerization is also critical for Ci-VSP function. Using coimmunoprecipitation and single-molecule pull-down, we find that Ci-VSP stoichiometry is flexible. It exists as both monomers and dimers, with dimers favored at higher concentrations. We show strong dimerization via the voltage-sensing domain (VSD) and weak dimerization via the phosphatase domain. Using voltage-clamp fluorometry, we also find that VSDs cooperate to lower the voltage dependence of activation, thus favoring the activation of Ci-VSP. Finally, using activity assays, we find that dimerization alters Ci-VSP substrate specificity such that only dimeric Ci-VSP is able to dephosphorylate the 3-phosphate from PI(3,4,5)P3 or PI(3,4)P2 Our results indicate that dimerization plays a significant role in Ci-VSP function.

PubMed ID: 29695412
PMC ID: PMC5940254
Article link: J Gen Physiol
Grant support: [+]

Species referenced: Xenopus
Genes referenced: asic1 kcnk2 myc

Article Images: [+] show captions
References [+] :
Anderluh, Direct PIP2 binding mediates stable oligomer formation of the serotonin transporter. 2017, Pubmed