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Results for “VENUS'S-FLYTRAP”

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4 recordsLinked to original sources
PubMed2001

The Venus's-flytrap and cysteine-rich domains of the human Ca2+ receptor are not linked by disulfide bonds.

The extracellular N-terminal domain of the human Ca(2+) 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 (Cys(129) and Cys(131)) were identified as involved in intermolecular disulfide bonds necessary for homodimerization, and six others (Cys(60)-Cys(101), Cys(358)-Cys(395), and Cys(437)-Cys(449)) 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 Cys(236) and Cys(482), 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.

Amino Acid Sequence↗
PubMed1982

Hinge-bending in L-arabinose-binding protein. The "Venus's-flytrap" model.

Theoretical conformational energy calculations show that large changes in the width of the binding-site cleft in the L-arabinose-binding protein involve only modest changes in the protein internal energy. Solvation energy changes associated with such variations of the cleft width and with protein-ligand interactions are estimated to be significantly larger than the internal energy changes. These results indicate that the binding-site cleft is open in the unliganded protein and is induced to close upon ligation. This picture is consistent with experimental data on the structure and binding kinetics of the L-arabinose-binding protein and provides a physical framework for interpreting such data.

Bacterial Proteins↗
PubMed2000

Human Ca2+ receptor cysteine-rich domain. Analysis of function of mutant and chimeric receptors.

The 612-residue extracellular domain of the human Ca(2+) receptor (hCaR) has been speculated to consist of a Venus's-flytrap domain (VFT) and a cysteine-rich domain. We studied the function of the hCaR Cys-rich domain by using mutagenesis and chimera approaches. A chimeric hCaR with the sequence from residues 540-601 replaced by the corresponding sequence from the Fugu CaR remained fully functional. Another chimeric hCaR with the same region of sequence replaced by the corresponding sequence from metabotropic glutamate receptor subtype 1 (mGluR1) still was activated by extracellular Ca(2+) ([Ca(2+)](o)), but its function was severely compromised. Chimeric receptors with the hCaR VFT and mGluR1 seven-transmembrane domain plus C-tail domain retained good response to [Ca(2+)](o) whether the Cys-rich domain was from hCaR or from mGluR1. Mutant hCaR with the Cys-rich domain deleted failed to respond to [Ca(2+)](o), although it was expressed at the cell surface and capable of dimerization. Our results indicate that the hCaR Cys-rich domain plays a critical role in signal transmission from VFT to seven-transmembrane domain. This domain tolerates a significant degree of amino acid substitution and may not be directly involved in the binding of [Ca(2+)](o).

Amino Acid Sequence↗