Zn(2+)-mediated domain-domain communication in human erythrocyte band 3.
Zn2+ could inhibit the anion transport activity of spectrin-stripped inside-out human erythrocyte membrane vesicles (IOVs). Removal of the cytoplasmic domain from Band 3 by trypsin could eliminate Zn2+ inhibition. The location of a Zn(2+)-binding site was confirmed by atomic absorbance spectrometry. The results of time-resolved fluorescence and intrinsic fluorescence quenching by KI and hypocrellin B (a photosensitive pigment obtained from a parasitic fungus growing in Yunnan, China) showed that the cytoplasmic domain is necessary for the Zn(2+)-induced conformational changes of the whole molecule as well as the membrane domain of Band 3. It is suggested that Zn2+ induced a conformational change in the cytoplasmic domain of Band 3, which in turn was transmitted to the membrane domain, resulting in an inhibition of activity of Band 3. Such long-range conformational changes may imply that the cytoplasmic domain is poised to function as a cytosolic arm in order to modulate the structure of the membrane domain of Band 3.
National Laboratory of Biomacromolecules, Institute of Biophysics, Academia Sinica, Beijing, China.
Y P
YP
Tu
F Y
FY
Yang
D001457:Anion Exchange Protein 1, Erythrocyte / Q000737:chemistry*; D001665:Binding Sites; D003593:Cytoplasm / Q000737:chemistry*; D004910:Erythrocyte Membrane / Q000737:chemistry / Q000187:drug effects*; D005470:Fluorometry; D006801:Humans; D008081:Liposomes; D017434:Protein Structure, Tertiary; D014357:Trypsin; D015032:Zinc / Q000494:pharmacology*
D001457:Anion Exchange Protein 1, Erythrocyte; D008081:Liposomes; D014357:Trypsin; D015032:Zinc