RT Journal Article SR Electronic T1 Influence of nanobody binding on fluorescence emission, mobility and organization of GFP-tagged proteins JF bioRxiv FD Cold Spring Harbor Laboratory SP 2020.06.11.146274 DO 10.1101/2020.06.11.146274 A1 Falk Schneider A1 Christian Eggeling A1 Erdinc Sezgin YR 2020 UL http://biorxiv.org/content/early/2020/06/11/2020.06.11.146274.abstract AB Advanced fluorescence microscopy studies require specific and monovalent molecular labelling with bright and photostable fluorophores. This necessity led to the widespread use of fluorescently labelled nanobodies against commonly employed fluorescent proteins. However, very little is known how these nanobodies influence their target molecules. Here, we observed clear changes of the fluorescence properties, mobility and organisation of green fluorescent protein (GFP) tagged proteins after labelling with an anti-GFP nanobody. Intriguingly, we did not observe any co-diffusion of fluorescently-labelled nanobodies with the GFP-labelled proteins. Our results suggest significant binding of the nanobodies to a non-emissive, oligomerized form of the fluorescent proteins, promoting disassembly into more monomeric forms after binding. Our findings show that great care must be taken when using nanobodies for studying dynamic and quantitative protein organisation.Competing Interest StatementThe authors have declared no competing interest.