Dear Leonid,

Yes it will. I regularly fill cells with neurobiotin or biocytin, and detect them using streptavidin conjugated cy3. I use standard 4% PFA for fixation. See my technical papers below in whole-mount retina and brain slices.

best wishes, Refik

Article Semi-loose seal Neurobiotin electroporation for combined str...

Article Neurobiotin Electroporation for Combined Structural and Func...

Thank you, Refik, very interesting papers.

Maybe I'm wrong but it seems to me, that you fix the biotin, not the streptavidin. The streptavidin, being a protein, can completely change its properties after fixation by PFA.

Dear Leonid,

Yes that is correct, I fix the biotin (Neurobiotin). Fixation is likely to change some properties of proteins but not all. I guess one needs to the opposite of my experiment, inject streptavidin into the cell, fix the tissue, and then incubate with biotin. 

best wishes, Refik

exactly, I want to know if the streptavidin conserves its biotin-binding properties upon fixation by the PFA.

Wow you can still use paraformaledhyde? He in the

Yes. it does retains its binding. I have used biotinylated antibody as a detection antibody and streptavidin one as a capture antibody on fixed cells and it totally worked.

Thank you, Shabnam,

Did you fixed your cells before or after the incubation with strep-antibodies?

Hi Leonid, im having the same problem here. Im using Streptavidin-Alexa 488 and fixation (previous to FACS) significantly reduces the signal. 

Very interesting question.

But , when i had fixed cells with 4% PFA , it didn't reduced much signal.For erythrocyte, 2% PFA also work fine.

Best regards, 

Babu