50kD cross-reacting protein with 12CA5

Lisa Frenz lfrenz at ns1.nimr.mrc.ac.uk
Mon Apr 20 06:39:39 EST 1998

> From: Namjin Chung <n.chung at duke.edu>
> Dear Netters,
> I have encountered a non-specific, cytosolic protein of about 50kD in
> size, which was recognized by anti-HA antibody (12CA5, monoclonal),
> while
> working with my protein of interest tagged with HA. Does anybody out
> there know the identity of this protein? Please email to
> n.chung at duke.edu if you have any slight clue. TIA.
> PS: I'm working with S. cerevisiae.

I am also working with cerevisiae and noted a 50kD protein recognised
non-specifically by the anti-HA 12CA5 antibody.  I find that this
non-specific band is strain dependent, with it appearing in the strain
cG378, but not in W303.  A paper in Gene 144 (1994) 63-68, by Foreman
and Davis, also reported observing a 50kD cross-reacting protein with
the 12CA5 antibody which was present in all the yeast cells examined,
although they don't state which strains they used.  They suggest that
problems which may be caused by the cross-reacting 50kD protein can be
overcome by preabsorbing the antibody with crude extract from yeast that
do not contain HA tagged proteins, prior to use.

Lisa Frenz

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