Many thanks – very interesting paper indeed!
Noam
From: Bonsor, Daniel [mailto:[log in to unmask]]
Sent: Thursday, September 22, 2016 3:44 PM
To:
אדיר נעם <[log in to unmask]>
Subject: Re: [ccp4bb] Overlapping isoforms
http://journals.iucr.org/m/issues/2016/04/00/jt5013/
This is a crystal of a milk protein that was isolated in vivo. There are isoforms in the structure. You can see the difference at certain positions in the density.
From: CCP4 bulletin board <[log in to unmask]> on behalf of Noam Adir <[log in to unmask]>
Sent: Thursday, September 22, 2016 6:31:14 AM
To: [log in to unmask]
Subject: [ccp4bb] Overlapping isoforms
Dear all,
We have recently determined the structure of a cyanobacterial protein to 2.1A where the asymmetric unit contains a heterodimer. Mass spectrometry of both solution and solubilized crystals show that we have a mixture of two isoforms of both
subunits – one is only a relatively minor heterogeneity (95% - 5%), but the second is larger, 70% vs. 30%. The sequence homology between these isoforms is 79% (34/162 non-identical residues) so the crystallographic heterogeneity is not insignificant. We have
not found a report of such a large degree of AU heterogeneity in the PDB or the literature – does someone know of a similar case?
Thanks,
Noam
