Bright and stable monomeric fluorescent proteins derived from StayGold

High brightness and photostability of StayGold make it a particularly attractive probe for long-term live cell imaging. However, its dimeric nature precludes its application as a fluorescent tag for proteins. Here, we report the development and X-ray structures of a monomeric variant of StayGold (mStayGold), which preserves the beneficial properties of its precursor while serving as a tag for structural proteins and membranes. We compare mStayGold to other state-of-art GFPs and utilize it for super-resolution long-term live cell imaging.