Measuring In Vivo Protein Half-Life

SummaryProtein turnover critically influences many biological functions, yet methods have been lacking to assess this parameter in vivo. Here, we demonstrate how chemical labeling of SNAP-tag fusion proteins can be exploited to measure the half-life of resident intracellular and extracellular proteins in living mice. First, we demonstrate that SNAP-tag substrates have wide bioavailability in mice and can be used for the specific in vivo labeling of SNAP-tag fusion proteins. We then apply near-infrared probes to perform noninvasive imaging of in vivo-labeled tumors. Finally, we use SNAP-mediated chemical pulse-chase labeling to perform measurement of the in vivo half-life of different extra- and intracellular proteins. These results open broad perspectives for studying protein function in living animals.

Graphical AbstractFigure optionsDownload high-quality image (251 K)Download as PowerPoint slideHighlights
► Fluorescent labeling of SNAP-tag fusion proteins is feasible in most mouse tissues
► NIR probes permit noninvasive detection of SNAP-tag fusion proteins in living mice
► SNAP-tag based chemical labeling allows measuring in vivo protein half-life