▁A ▁fusion ▁of ▁E c F b FP ▁and ▁Y FP ▁was ▁e . g . ▁used ▁to ▁develop ▁the ▁first ▁gen et ically ▁encoded ▁flu ores c ence ▁b ios ensor ▁for ▁o xygen ▁( F lu BO ) ▁ ▁The ▁main ▁dis adv antage ▁compared ▁to ▁G FP ▁variants ▁is ▁their ▁lower ▁bright ness ▁( the ▁product ▁of ▁ ε ▁and ▁ Φ ). ▁The ▁commonly ▁used ▁E G FP ▁( ε ▁= ▁ 5 5 , 0 0 0 ▁M − 1 cm − 1 ; ▁ Φ ▁= ▁ 0 . 6 0 ▁) ▁for ▁example ▁is ▁approximately ▁five ▁times ▁as ▁bright ▁as ▁E c F b FP . ▁Another ▁dis adv antage ▁of ▁the ▁F b FP s ▁is ▁the ▁lack ▁of ▁color ▁variants ▁to ▁tag ▁and ▁distinguish ▁multiple ▁prote ins ▁in ▁a ▁single ▁cell ▁or ▁t issue . ▁The ▁largest ▁spectral ▁shift ▁reported ▁for ▁F b FP s ▁so ▁far ▁is ▁ 1 0   nm . ▁Although ▁this ▁variant ▁( P p 2 F b FP ▁Q 1 1 6 V ) ▁can ▁be ▁vis ually ▁distinguished ▁from ▁the ▁others ▁with ▁the ▁human ▁eye , ▁the ▁spectral ▁differences ▁are ▁too ▁small ▁for ▁flu ores c ence ▁micro sc opy ▁filters . ▁ ▁References ▁▁ ▁Category : Re com bin ant ▁prote ins ▁Category : Pro te in ▁imag ing ▁Category : Pro te in ▁methods ▁Category : Cell ▁imag ing ▁Category : F lu ores cent ▁prote ins ▁Category : Bi ol um ines c ence