Question (36362) | Anti-Otx1 + Otx2 antibody - ChIP Grade (ab21990)

Go to datasheet (ab21990)


Here is the link to ab92515 ( The western has a single band close to the 25kD marker band.    While the ab21990 has two bands one just above 25kD and one at 37kD. Since 21990 detects both OTX1 (37kD) and OTX2 (32kD) I assume my lower band is OTX2. But if ab92515 detects both proteins then why don’t we see two bands?   Whereas ab76748 that you suggested previously doesn’t have any western images in the datasheet.   I am trying to estimate amounts of OTX2 only. And this is important hence all the questions.  


Thank you for getting back to me with these questions.

I have been under the assumption that you havwe been using ab21190 for your experiments, have you been using ab92515 as well?Based on sequence homology ab92515 will recognize both proteins. The absence of a second band in the image is unresolved but may be due to poor separation or extrememly low levels of Otx1 in the sample.

Using ab21190 the lower band will be Otx2 which, in either isoform, has a lower molecular weight that Otx1. (

Although ab76748 does not have any western blot images in the datasheet we have been assured that the immunogen used for this has no cross reactivity to Otx1.This product is guaranteed to work in western bloton ​human tissues and is covered by our Abpromise for a period of six months. Since we have been unable to resolve this problem, if you have purchased this product within the last 180 days, I would be happy to either send this replacement antibody or to process a refund. If you could please supply me with your Abcam order confirmation number for the purchase of ab21190 I can begin to process this replacement,

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