[Arabidopsis] Can overly expressed GFP by 35S be a secretory protein?

[John Runions]

   Dear Hee-Jin,
   I suspect that Tobias is absolutely correct about the low pH quenching
   the fluorescence of GFP in the apoplast.  As evidence of this, we have
   two fusions that should mark the Golgi bodies; 35s ST-GFP and 35s
   ST-mRFP.  Both mark Golgi bodies beautifully and the ST-mRFP shows up
   very brightly in the apoplast marking all of the cell boundaries.
   There is no reason why one version of this should be secreted when the
   other isn't.
   Regards, John.
   Hee-Jin Kim wrote:
   
Dear Arab-gen and colleagues 

How are you doing?

Does anybody know if overly expressed GFP with 35S can be found extracellular f
raction of cells in addition to the typical localizations (cytoplasm and nucleo
plasm) of GFP ?  One of my soluble protein (no  signal peptide), abundantly ove
r-expressed mGFP5 fusion with 35S  was found in the cell wall fractions by West
ern blot although microscopic picture showed most portion of the fusion protein
 is in cytoplasm.  

I found a paper that 31% of overly expressed mGFP5-ER with 35S in BY2 was secre
ted into medium according to Western blot analyses (Liu et al., 2001, J Biotech
nology 87: 1-16).  However,  I could not find so far if overly expressed GFP al
one in plant cells can be secreted.   
Any comment how the levels of GFP expressions can affect localization would be 
appreciated.  

Hee-Jin 
 




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   C. John Runions, Ph.D.
   School of Life Sciences
   Oxford Brookes University
   Oxford, UK
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   New - Oxford Brookes Master's in [5]Bioimaging with Molecular
   Technology

References

   1. mailto:Arab-gen At net.bio.net
   2. http://www.bio.net/biomail/listinfo/arab-gen
   3. mailto:jrunions At brookes.ac.uk
   4. http://www.brookes.ac.uk/lifesci/runions/HTMLpages/index.html
   5. http://www.brookes.ac.uk/go/bioimaging_masters