Anti-BMP4 antibody (ab38342)

Dear Abcam,
Recently our department aquired your antibody ab38342 for human BMP4. Upon testing it however,
we where struck with confusing results, on wich I would really appreciate your imput.
Attacked you will find a picture of one of our test blots.On here we tested out sheep sample against
a human lung lysate positive control. This for us seemed the best positive control,
since the antibody in question was raised against human BMP4. However,
we noticed the control band not to be at all where we where expecting it.
In a different experiment we tested a different secondary antibody aswell,
giving similar results. Also to note,
the band in out sheep sample seems to correspont with the epitope size of this antibody.
So in short, any suggestions why we see this diversity of band size and
why the positive control is not where abcam says is should be, would be greatly appreciated.
We simply think the difference is to great,
seeing as the sample should be very similar to your own sample when first establishing its use in Western Blot.
Any reaction would be greatly appreciated!
Kind regards,
P.s. If you require further details, please feel free to contact me.

ANSWER:

Thank you for your inquiry.
The image you send me shows a band at ca 60kDa for the human sample and a band at ca 15kDa for the sheep sample.
The predicted size of BMP4 is 45kDa. According to the SwissProt site this protein is also glycosylated on multiple residues which will lead to a higher band on the gel.
I checked for the homology of the immunogen with sheep and found only a 78% homology. We usually expect a cross reaction of an antibody at a homology of 85% and higher. This antibody has not been tested by us to work with sheep and is therefore not covered by our guarantee for sheep.
According to our records we offered you to take part in the testing discount program testing a different BMP4 antibody where the immunogen shows a higher homology to the sheep sequence. Maybe this antibody would be more suitable for your experiments.
Please let me know if you have any further concerns.