Semisynthetic fluorescent pH sensors for imaging exocytosis and endocytosis

Nature Communications (2017)

Magalie Martineau, Agila Somasundaram, Jonathan B Grimm, Todd D Gruber, Daniel Choquet, Justin W Taraska, Luke D Lavis & David Perrais

The GFP-based superecliptic pHluorin (SEP) enables detection of exocytosis and endocytosis, but its performance has not been duplicated in red fluorescent protein scaffolds. Here we describe ‘semisynthetic’ pH-sensitive protein conjugates with organic fluorophores, carbofluorescein and Virginia Orange, that match the properties of SEP. Conjugation to genetically encoded self-labeling tags or antibodies allows visualization of both exocytosis and endocytosis, constituting new bright sensors for these key steps of synaptic transmission.