Citrine is a monomeric, acid-resistant yellow fluorescent protein with an excitation peak of 516nm and an emission peak of 529nm in vitro (PMID:20664080, PMID:11387331). It is an artificial derivative of the naturally occurring fluorescent protein encoded by the Aequorea victoria GFP gene (UniProtKB:P42212), containing the mutations S65G, V68L, Q69M, S72A, T203Y (PMID:11387331).