Evidence for multisite allosteric interactions on the band 3 monomer.

Pyridoxal-5'-phosphate is known to label the two integral, chymotryptic domains (CH17 and CH35) of the erythrocyte anion exchange protein known as band 3. The CH35 sites are mutually exclusive with stilbene disulfonate binding, while the CH17 sites are not. Selective, irreversible pyridoxal-5'-phosphate labeling of CH17, reduces the transport inhibitory potency due to reversible stilbene disulfonate binding to vacant, nonoverlapping CH35 sites. We conclude that multisite allosteric interactions can occur on one band 3 monomer.