Structural requirements for the stabilization of metarhodopsin II by the C terminus of the alpha subunit of transducin
| Autor: | Peter J. Schatz, Heidi E. Hamm, Edward A. Dratz, Annette Gilchrist, Lida Aris, Carna Meyer, Stephanie Rens-Domiano |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
Conformational change
Rhodopsin G protein Stereochemistry Glycine Biochemistry Heterotrimeric G protein Amino Acid Sequence Cysteine Transducin Molecular Biology Peptide sequence Conserved Sequence biology Chemistry C-terminus Lysine Cell Biology META II Peptide Fragments Protein Subunits biology.protein sense organs Protein Binding |
| Zdroj: | The Journal of biological chemistry. 276(4) |
| ISSN: | 0021-9258 |
| Popis: | The retinal receptor rhodopsin undergoes a conformational change upon light excitation to form metarhodopsin II (Meta II), which allows interaction and activation of its cognate G protein, transducin (G(t)). A C-terminal 11-amino acid peptide from transducin, G(talpha)-(340-350), has been shown to both bind and stabilize the Meta II conformation, mimicking heterotrimeric G(t). Using a combinatorial library we identified analogs of G(talpha)-(340-350) that bound light-activated rhodopsin with high affinity (Martin, E. L., Rens-Domiano, S., Schatz, P. J., and Hamm, H. E. (1996) J. Biol. Chem. 271, 361-366). We have made peptides with key substitutions either on the background of the native G(talpha)-(340-350) sequence or on the high affinity sequences and used the stabilization of Meta II as a tool to determine which amino acids are critical in G protein-rhodopsin interaction. Removal of the positive charge at the N termini by acylation or delocalization of the charge by K to R substitution enhances the affinity of the G(talpha)-(340-350) peptides for Meta II, whereas a decrease was observed following C-terminal amidation. Cys-347, a residue conserved in pertussis toxin-sensitive G proteins, was shown to interact with a hydrophobic site in Meta II. These studies provide further insight into the mechanism of interaction between the G(talpha) C terminus and light-activated rhodopsin. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|