pH Indicators

Numerous physiological functions, such as the contraction of muscles, the transmission of nerve impulses, and cell signaling, are heavily dependent on variations in intracellular pH. The shift in intracellular pH might occur gradually, with variations occurring only in fractions of a pH unit. These days, Creative Biolabs provides a variety of innovative indicators that let you keep an eye on the pH in the cytoplasm, particularly in organelles.

pH indicators at Creative Biolabs

Functional Gene	Description
pHTomato	pHTomato is a bright, red, pH-sensitive, genetically encoded probe. This probe can be used to construct indicators that allow imaging of neurotransmitter release to monitor neuronal activity and the tight size match between pre- and postsynaptic compartments, as well as the intriguing target cell-dependent regulation of presynaptic vesicles observed in cisternae.
pHoran4	pHoran4 is a subset of the pH-sensitive mOrange proteins characterized by the M163K mutation near the chromophore. This probe demonstrates the key role of this residue in regulating the pH sensitivity of discoid red fluorescent protein variants.
pHmScarlet	pHmScarlet is a red fluorescent protein probe with excellent brightness, stability, and pH sensitivity. This probe has the highest pH sensitivity of any existing red fluorescent protein, can detect more secretion events, and can identify both the vesicle anchoring and fusing processes of secretion events.
pHuji	pHuj is derived from the red fluorescent protein mApple K163Y, a variant that exhibits fluorescence intensity by more than 20-fold between pH 5.5 and 7.5. pHuji is ideal for the detection of individual exocytosis and endocytosis events.
pHRed	pHRed is a red fluorescent protein (RFP) that combines with the pH sensitivity of the A213S mutant. pHRed can detect intracellular pH fluctuations by imaging energy-dependent changes in cytosolic and mitochondrial pH.

Case Study

By combining sypHTomato with a green calcium indicator like GCaMP3, both processes can be observed in a single nerve terminal. When sypHTomato and GCaMP3 were co-transfected into cultured hippocampal neurons, sypHTomato was shown to be more prevalent in presynaptic boutons whereas GCaMP3 was more uniformly distributed.

Fig 1 Dual-color imaging of pHTomato and [Ca²⁺] cytosolic and vesicle fusion from the same neuron. Dual-color time-lapse recordings of GCaMP3 signals (reporting [Ca²⁺] cytosolic) and SypHTomato signals (reflecting vesicle fusion) were obtained by imaging in the same cultured hippocampal neurons.¹

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Reference

Li, Yulong, and Richard W. Tsien. "pHTomato, a red, genetically encoded indicator that enables multiplex interrogation of synaptic activity." Nature neuroscience 15.7 (2012): 1047-1053.

For Research Use Only. Not For Clinical Use.