Description
KFP-Red is a photoactivatable GFP-like protein capable for switching from nonfluorescent to bright red fluorescent form and back in response to light of certain intensity and wavelength. KFP-Red allows to monitor cell and subcellular structure movement in living tissues and represents an unique tool to study morphogenesis, inflammation, metastasis, investigate mitochondria role in apoptosis, vesicular and axonal transport, etc. KFP-Red is photoactivated under green light (530-560 nm) that do not damage cells or tissues. Depending on kindling light intensity KFP-Red can be kindled reversibly or irreversibly. Reversibly kindled KFP-Red relaxes to the initial non-fluorescent form (half-life 50 seconds), or can be quenched instantly by blue light (430-490 nm). It fluoresces at least 70 times brighter than before kindling. Reversible kindling and quenching can be repeated indefinitely. Irreversibly kindled KFP-Red gives stable red fluorescence which is at least 35 times brighter than that before kindling. It remains stable and brightly fluorescent for more than 72 hours in living cells and for at least one year in protein samples. Irreversibly kindled KFP-Red can be partially quenched by blue light, but then restores its brightness within several minutes. Therefore, in some applications, blue light can be used to quench reversibly kindled KFP-Red, while irreversibly kindled KFP-Red remains fluorescent. Green light of low intensity does not cause kindling and may be used as excitation light to monitor kindled KFP-Red bright red fluorescence under regular fluorescent microscope. pKindling-Red-mito is a mammalian expression vector encoding KFP-Red fused with mitochondrial targeting sequence of human cytochrome C oxidase subunit VIII precursor. pKindling-Red-mito vector is designed for photo-inducible fluorescent labeling of mitochondria and tracking of mitochondrial movement.