▁dis adv antages ▁ ▁The ▁main ▁advantage ▁of ▁F b FP s ▁over ▁G FP ▁is ▁their ▁independence ▁of ▁mole cular ▁o xygen . ▁Since ▁all ▁G FP ▁derivatives ▁and ▁hom olog ues ▁require ▁mole cular ▁o xygen ▁for ▁the ▁m atur ation ▁of ▁their ▁chrom oph ore , ▁these ▁flu ores cent ▁prote ins ▁are ▁of ▁limited ▁use ▁under ▁an a er ob ic ▁or ▁hy po xic ▁conditions . ▁ ▁Since ▁F b FP s ▁bind ▁FM N ▁as ▁chrom oph ore , ▁which ▁is ▁synth es ized ▁independently ▁of ▁mole cular ▁o xygen , ▁their ▁flu ores c ence ▁signal ▁does ▁not ▁differ ▁between ▁aer ob ic ▁and ▁an a er ob ic ▁conditions . ▁Another ▁advantage ▁is ▁the ▁small ▁size ▁of ▁F b FP s , ▁which ▁is ▁typically ▁between ▁ 1 0 0 ▁and ▁ 1 5 0 ▁am ino ▁ac ids . ▁This ▁is ▁about ▁half ▁the ▁size ▁of ▁G FP ▁( 2 3 8 ▁am ino ▁ac ids ). ▁It ▁could ▁for ▁example ▁be ▁shown ▁that ▁this ▁rend ers ▁them ▁superior ▁tags ▁for ▁monitoring ▁to b acco ▁m osa ic ▁virus ▁in fe ctions ▁in ▁to b acco ▁leaves . ▁Due ▁to ▁their ▁extraordinary ▁long ▁average ▁flu ores c ence ▁lifetime ▁of ▁up ▁to ▁ 5 . 7 ▁ns ▁they ▁are ▁also ▁very ▁well ▁su ited ▁for ▁the ▁use ▁as ▁don or ▁domains ▁in ▁F RE T ▁systems ▁in ▁conj unction ▁with ▁e . g . ▁Y FP ▁( see ▁phot oph ys ical ▁properties ).