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Table 2 FLIM assay detects SPP dimer formation of epitope tagged SPP constructs.

From: Signal peptide peptidase (SPP) dimer formation as assessed by fluorescence lifetime imaging microscopy (FLIM) in intact cells

Donor (Alexa 488 labeled)

Acceptor (Cy3 labeled)

Alexa 488 Lifetime (mean ± st.err, psec)

P value (Compared to Alexa donor only)

SPPCTV5* (n = 18)

None

2504 ± 84

-

SPPCTV5* (n = 18)

SPPNTFLAG**

1978 ± 66

<0.001

SPPCTV5* (n = 5)

Anti-goat IgG

1328 ± 58

<0.001

  1. *Goat Anti-V5
  2. **Mouse Anti-FLAG
  3. SPP dimer formation between all combinations of epitope tagged SPP constructs was demonstrated by significant shortening of donor lifetime. HEK 293 cells stably overexpressing SPPCTV5 and SPPNTFLAG. Alexa 488 labeled SPPCTV5 donor fluorophore lifetime was significantly shortened in the presence of either Cy3 labeled SPPNTFLAG or Cy3 labeled anti-goat IgG (positive control). ANOVA was performed using a Dunnet's post-hoc t-test.