Salhany J M, Cordes K A
Department of Veterans Affairs Medical Center, Omaha, Nebraska.
Biochem Biophys Res Commun. 1991 Jan 31;174(2):975-82. doi: 10.1016/0006-291x(91)91514-d.
Calcium is known to be a potent but partial intracellular inhibitor of band 3 anion exchange. Here we test the hypothesis that the cytoplasmic domain of band 3 (CDB3) contains a calcium binding site. Calcium binding to CDB3 was monitored by measuring the formation of the Aresenazo III-calcium complex at various constant CDB3 concentrations. These experiments were performed at physiological salt and neutral pH. The calcium-CDB3 dissociation constant was estimated to be less than or equal to 24 microM. We also found that the Arsenazo III-calcium complex binds to CDB3, while the free dye does not bind. We conclude that CDB3 contains a site which is capable of binding free calcium under physiological conditions. A specific role for this site in inhibition of band 3 anion exchange is suggested, but that role remains to be established.
已知钙是带3阴离子交换的一种强效但部分性的细胞内抑制剂。在此，我们检验了一个假说，即带3的细胞质结构域（CDB3）含有一个钙结合位点。通过在各种恒定的CDB3浓度下测量偶氮胂III -钙复合物的形成来监测钙与CDB3的结合。这些实验是在生理盐浓度和中性pH条件下进行的。钙 - CDB3解离常数估计小于或等于24微摩尔。我们还发现偶氮胂III -钙复合物与CDB3结合，而游离染料不结合。我们得出结论，CDB3含有一个在生理条件下能够结合游离钙的位点。有人提出该位点在抑制带3阴离子交换中具有特定作用，但该作用仍有待确定。
