What impact does the expression system have on the post-translational modification of GFP?

The choice highlighting that the expression system leads to variations in glycosylation or folding is particularly significant because post-translational modifications, including glycosylation and how proteins fold, are closely tied to the cellular machinery utilized in the expression system. Different organisms, such as bacteria, yeast, or mammalian cells, have varying capabilities for processing proteins after translation.

For instance, mammalian cells are often capable of adding complex glycan structures that can influence a protein's function and stability, while bacterial systems lack the enzymes necessary for many of these modifications and perform simple modifications instead. Additionally, proteins may fold differently depending on the environment of the expression system, significantly affecting their functionality and, by extension, their use in applications like fluorescence. Thus, understanding how the expression system affects these processes is crucial in optimizing GFP purification and ensuring that the protein possesses the desired characteristics for research or medical applications.