The Venus's-flytrap and Cysteine-rich Domains of the Human Ca2+ Receptor are Not Linked by Disulfide Bonds

Jianxin Hu, Guadalupe Reyes-Cruz, Paul K. Goldsmith, Allen M. Spiegel

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20 Scopus citations


The extracellular N-terminal domain of the human Ca2+ receptor (hCaR) consists of a Venus's-flytrap (VFT) domain and a cysteine-rich (Cys-rich) domain. We have shown earlier that the Cys-rich domain is critical for signal transmission from the VFT domain to the seven-transmembrane domain. The VFT domain contains 10 cysteines: two of them (Cys129 and Cys 131) were identified as involved in intermolecular disulfide bonds necessary for homodimerization, and six others (Cys60-Cys 101, Cys358-Cys395, and Cys 437-Cys449) are predicted to form three intramolecular disulfide bonds. The Cys-rich domain contains nine cysteines, the involvement of which in disulfide bond formation has not been defined. In this work, we asked whether the remaining cysteines in the hCaR VFT, namely Cys236 and Cys482, form disulfide bond(s) with cysteines in the Cys-rich domain. We constructed mutant hCaRs with a unique tobacco etch virus (TEV) protease recognition site inserted between the VFT domain and the Cys-rich domain. These mutant hCaRs remain fully functional compared with the wild type hCaR. After TEV protease digestion of the mutant hCaR proteins, dimers of the VFT were identified on Western blot under nonreducing conditions. We concluded that there is no disulfide bond between the VFT and the Cys-rich domains in the hCaR.

Original languageEnglish (US)
Pages (from-to)6901-6904
Number of pages4
JournalJournal of Biological Chemistry
Issue number10
StatePublished - Mar 9 2001
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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