TPE-MI (Tetraphenylethene maleimide) serves as a thiol probe that measures the load of unfolded proteins and monitors proteostasis in cells. It can indicate proteostasis imbalances in induced pluripotent stem cell models of Huntington's disease and in cells transfected with mutant Huntington exon 1 before aggregates become visible. TPE-MI also identifies protein damage in studies involving the malaria parasite Plasmodium falciparum[1][2].
体外研究
TPE-MI is non-fluorescent until it binds to a thiol group through its maleimide group. Its fluorescence is activated when it labels free cysteine thiols, which are typically hidden inside globular proteins but become exposed when the proteins unfold[1].
In live HeLa cells, TPE-MI at 50 μM for up to 60 minutes displays a uniform cytoplasmic labeling pattern, with less labeling in the nucleus and a concentration near the endoplasmic reticulum, a key site for protein synthesis and folding[1].
In cells expressing the mutant 97Q form of Httex1 at high levels, there is an increased TPE-MI fluorescence signal compared to cells expressing the non-disease causing 25Q form of Httex1[1].
TPE-MI combines the aggregation-induced emission (AIE) fluorogen tetraphenylethane (TPE) with the thiol-reactive maleimide (MI) group, featuring both AIE properties and selective reactivity towards thiols[2].
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