Many signal transduction processes are regulated by GTP binding proteins (G-proteins) like small GTPases → Proteins of the Ras superfamily or heterotrimeric G-proteins → Proteins. The G-proteins act as molecular switches cycling between an inactive GDP-bound and an active GTP-bound state[1].
GTP and GDP analogs with various modifications have become indispensable tools to study G-protein signaling. In general, GTP and GDP analogs containing a modified phosphate moiety are resistant to enzymatic hydrolysis or are hydrolyzed at much smaller rates compared to their natural counterparts (non-hydrolyzable nucleotides).
2'/3'-Mant-,TNT- and Ant-modified GTP and GDP analogs combine fluorescence with close mimicry of the properties of natural nucleotides in respect of protein binding and interaction. They display environmentally sensitive fluorescence and therefore give strong signals upon a binding event which makes them perfect probes for stopped-flow and equilibrium analysis.
For detailed application data please refer to the corresponding data sheets.
| GTP Analog | Modification | |
|---|---|---|
| instrinsically fluorescent | Mant-GTP | ribose moiety (2'/3'-OH) |
| TNP-GTP | ||
| Ant-GTP | ||
| Non-hydrolyzable | GTPαS | α-phosphate moiety |
| GTPγS | γ-phosphate moiety | |
| Mant-GTPγS* | ||
| GpCpp | α, β-phosphate moiety | |
| GppCp | β, γ-phosphate moiety | |
| GppNHp | ||
| Mant-GppNHp* | ||
| TNP-GppNHp* |
* These nucleotides possess both non-hydrolyzable and intrinsically fluorescent properties.
[1] Vetter et al. (2001) The guanine nucleotide-binding switch in three dimensions. Science 294 (5545):1299.
