SLIM
GFP with short fluorescence lifetime

- Green fluorescence
- Short fluorescence lifetime (1300 ps, in vitro)
- Recommended for fluorescence lifetime imaging microscopy (FLIM)
- Fast maturation and high photostability

SLIM (Shortened Lifetime Imaging Marker) is a highly photostable green fluorescent protein with fluorescence lifetime shortened/reduced relative to the common GFPs (1300 ps vs 2.5-3 ns) [Mamontova et al., 2018]. SLIM carries glycine-tyrosine-glycine (GYG) chromophore and demonstrates fast chromophore maturation under physiological conditions. It also shows weak reactivity in excited-state redox-chemistry and thus – low phototoxicity. For multiparameter FLIM in green channel SLIM can be used with fluorescent proteins with similar fluorescence spectra and different fluorescence lifetimes: BrUSLEE (800 ps), SLIM (1.3 ns), TagGFP2 (3.2 ns).

Main properties

SLIM normalized excitation (thin line) and emission (thick line) spectra. Download SLIM spectra (xls)

CHARACTERISTIC * Brightness is a product of extinction coefficient and quantum yield, divided by 1000. Molecular weight, kDa 27 Polypeptide length, aa 239 Fluorescence color green Excitation maximum, nm 488 Emission maximum, nm 508 Quantum yield 0.06 Extinction coefficient, M-1cm-1 70 000 Brightness* 4.2 Brightness, % of EGFP 13 Fluorescence lifetime, ps 1300 Fluorescence intensity decay nearly single-exponential Aggregation no Maturation rate at 37°C fast Photostability high Cell toxicity not observed Main advantages green fluorescent protein with shortened fluorescence lifetime

Recommended filter sets and antibodies

The protein can be recognized using Anti-Tag(CGY)FP antibody (Cat.# AB121) or Anti-GFP antibody (Cat.# AB011) available from Evrogen.

SLIM can be detected using common fluorescence filter sets for EGFP, FITC, and other green dyes. Recommended Omega Optical filter sets are QMAX-Green, XF100-2, XF100-3, XF115-2, and XF116-2.

Performance and use

SLIM can be easily expressed and detected in a wide range of organisms. Mammalian cells transiently transfected with SLIM expression vectors produce bright fluorescence in 16-18 hrs after transfection. No cytotoxic effects or visible protein aggregation are observed.

It can be used in multiparameter FLIM in green channel.

	Color-coded fluorescence lifetime imaging microscopy (FLIM) image of live HeLa cells co-expressing BrUSLEE (mitochondria), SLIM (nuclei) and TagGFP2 (cytoplasm). Color hue indicates mean lifetime at each pixel (red-orange – 750-900 ps, green – 1100-1400 ps, cyan-blue – 2700-3100 ps). Single-photon fluorescence excitation at 488 nm was used to acquire these images.

Available variants and fusions

Variant	Description	Related vector	Cat.#
Humanized SLIM	SLIM codon usage is optimized for high expression in mammalian cells [Haas et al., 1996], but it can be successfully expressed in many other heterological systems.	pSLIM-N	FP212