Hi Steven,
 
According to Molecular Probes, streptavidin may have the ability to bind
specifically to certain integrins and other cell surface proteins (using an
RYD sequence that binds similarly to the RGD sequence of fibronectin), they
market a charge-stripped avidin (which doesn't have the motif, and doesn't
have avidin's drawback of binding to charged moieties).  It's called
Neutralite Avidin, and is available conjugated to Texas Red and
R-Phycoerythrin.
 
We tried the R-PE version a few years back and it seemed to solve our
problem, and it might be worth your while giving it a go, if you've got the
right filters.
 
Ray
 
 
 
>I have just performed some experiments on frozen pituitary sections
>and found that my TRITC streptavadin (Zymed) is sticking directly to
>the tissues even in the absence of the primary and biotinylated
>secondary.
>Does anyone have any suggestions of how to overcome this problem,
>other than to try another secondary antibody which is directly
>coupled to a fluorophore (other than FITC, as i intend to double
>label).
>
>Thanks in advance
>
>Steven
 
                              Ray Hicks
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