Fluorescent protein spectra

Abstract

ABSTRACT The cloning of the green fluorescent protein (GFP) from the jellyfish Aequoria victoria and its expression in heterologous systems was a significant advance for optical microscopy of living cells (Chalfie et al., 1994). Mutagenesis of jellyfish GFP has yielded proteins that fluoresce from blue to yellowish green, and genetic manipulations have generated GFP variants that are better suited for fluorescence microscopy than wild-type GFP and have optimized codon usage (Tsien, R. Y., 1998). For example, a green color variant of Aequoria GFP (EGFP) has been extensively used as an in vivo reporter because of its high quantum yield and resistance to photobleaching. However, the useful cyan fluorescent variant (ECFP) has low absorption and low quantum yield, whereas the yellowish-green fluorescent protein (EYFP) has the highest absorption and quantum yield but is more susceptible to photobleaching than are most other mutants. The recent cloning of a gene that encodes a red fluorescent protein (dsRed) from the Indo-Pacific sea anemone Discosoma striata has provided yet another fluorescent protein that is further red-shifted (Matz, M. V. et al. 1999). The dsRed shares only ∼25% sequence identity with Aequoria GFP; other usable GFPs are therefore likely to be discovered in the future. Several limitations to the use of dsRed have been identified, including slow protein maturation and a strong tendency to form tetramers (Baird, G. S., et al. 2000).