Se-mediated domain-domain communication in band 3 of human erythrocytes.
Na2SeO3 could affect the anion flux of Band 3 of inside-out erythrocyte membrane vesicles (IOVs). Such effect was believed to be based on the interaction of SH groups of Band 3 with Na2SeO3. This effect could be eliminated when the cytoplasmic domain of Band 3 was proteolytically removed by trypsin. This suggested that SH groups in the cytoplasmic domain were involved in such interaction. Measurement of the pH dependence of intrinsic fluorescence intensity provided evidence that conformational changes of Band 3 occurred as a consequence of interaction with selenite. KI quenching of intrinsic fluorescence of Band 3 could also show that there was a conformational change in the cytoplasmic domain of Band 3 after reaction with Na2SeO3. Such conformational change in turn could be transmitted to the membrane domain of Band 3 monitored by quenching of intrinsic fluorescence of Band 3 using hypocrellin B (HB) (a photosensitive pigment obtained from a parasitic fungus growing in Yunnan, China). It is suggested that the cytoplasmic domain of Band 3 is not necessary for its anion flux, but is essential for the regulation (e.g., by Se) of its active site located at the membrane domain, and hence, it may provide evidence of communication between the cytoplasmic domain and the membrane domain of Band 3.
Yang
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FY
National Laboratory of Biomacromolecules, Institute of Biophysics, Academia Sinica, Beijing, China.
Fen
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C
Tu
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YP
D001457:Anion Exchange Protein 1, Erythrocyte / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D002450:Cell Communication / Q000187:drug effects; D003593:Cytoplasm / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D005453:Fluorescence; D006801:Humans; D006863:Hydrogen-Ion Concentration; D017136:Ion Transport / Q000187:drug effects; D011487:Protein Conformation; D018038:Sodium Selenite / Q000494:pharmacology*; D013438:Sulfhydryl Compounds / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism; D018909:src Homology Domains / Q000187:drug effects*
D001457:Anion Exchange Protein 1, Erythrocyte; D013438:Sulfhydryl Compounds; D014357:Trypsin; D018038:Sodium Selenite