A note to our Drosophila colleagues using the FLAG epitope-tagging system:
In studying the expression and distribution in Drosophila of protein tagged
with the FLAG epitope, it has been our experience that there are at least
two endogenous Drosophila proteins both in embryos and adults that
cross-react strongly on Western blots with the commercially available
anti-FLAG M2 monoclonal antibody. This cross reactivity may also cause
problems in the interpretation of other immunohistochemical results.
In conversation with Bill Brizzard at Kodak, we became aware that there was
another monoclonal, M5, which was available in small quantities but not yet
placed on the market. We tested this monoclonal and found it to be highly
specific for the epitope-tagged proteins. In our hands, it has given a
strong signal in both Western blot and immunostaining experiments and is
clearly superior to the M2 monoclonal for use with the FLAG epitope in
We have been informed that the M5 antibody has now become available for
sale from Kodak (catalog numbers IB13090, IB13091, IB13092) and can be
ordered from their Customer Service at 800-225-5352. It should be
available from their normal distributors in the near future.
Disclaimer: This message is not intended to be advertising for any
particular epitope-tagging method or product or company, and neither of us
has any financial connection with Kodak or its subsidiaries.
----- Kati Afshar (kafshar at ucdavis.edu) & Ken Burtis (kcburtis at ucdavis.edu)