Susann Meyer

Legend to the graphic: Newly made proteins incorporate a label consisting of the essential amino acid leucine containing the rare nitrogen isotope ¹⁵N. This label allows the detection of newly made proteins in individual synapses by imaging mass spectrometry. The activity of the same synapses was determined with fluorescence microscopy. These combined measurements confirmed the model prediction that synaptic boutons have a demand-dependent supply of synaptic vesicles: more active presynapses have more newly made synaptic proteins. This correlation was disrupted by chronic activation or inhibition of synaptic activity. (Graphic: Cell Reports/ Sebastian Jähne, UMG)