There have been several reports that the cholera toxin B-subunit (CTB) does not bind to blood group oligosaccharides; [10] however, most binding studies appear to have been undertaken using classical biotype CTB, rather than El Tor CTB.
Finally, the digoxigenin-binding anticalins appear to have high physico-chemical stability, with Tm values in the 70 °C range.
The IgE-binding proteins appear to have mainly acidic pI values (pI about 5).
This observation suggests that during the evolution of caleosin, sites in the Ca2+-binding motif appear to have coevolved.
Similar interactions of aromatic amino acid residues with the guanine nucleotide of cap-analogues are seen in the structures of other cap-binding proteins which appear to have evolved independently such as the vaccinia virus 2'-O-methyltransferase, VP39, and of the nuclear cap-binding protein subunit, CBP20, suggesting a common evolutionary theme for methylguanosine/nucleotide-interaction [ 7].
In this case, after evolution of the binding pocket, docking motifs appear to have arisen ex nihilo in disordered regions of proteins that were already Cbk1 substrates, and were subsequently preserved over evolution.
We also analyzed a more densely sampled set of vertebrate genomes to find out whether SP1-binding site consensus sequences appear to have changed in other lineages.
Putative D. melanogaster orthologues could be assigned for the majority of the presumably ligand-binding CstyORs; however, 13 appear to have no D. melanogaster counterpart.
The third issue is the resulting structural/electronic-structure consequences of the identity of the trans ligand in exo versus endo N2 binding, and it does not appear to have been widely discussed.
TBP and SNAP50 appear to bind to all RNA polymerase II and III promoters and appear to have identical binding patterns genome-wide, laying open the interesting possibility that SNAPc may serve as a general transcription factor for protein-coding transcription in these organisms.
