Sequence encoding a linker and the Dendra2 photoconvertible fluorescent protein has been inserted into the endogenous His3.3A locus, at the C-terminal end of the open reading frame. In addition, a S31A amino acid replacement has been introduced into the His3.3A coding sequence; this changes the amino acid, which is normally a phosphorylation site in the His3.3A protein, to that found in the His3 coding sequence.