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Second transmembrane domain of human uncoupling protein 2 is essential for its anion channel formation
Author(s) -
Yamaguchi Hiroshi,
Jelokhani-Niaraki Masoud,
Kodama Hiroaki
Publication year - 2004
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2004.09.070
Subject(s) - chemistry , ion channel , transmembrane protein , biophysics , transmembrane domain , ion transporter , ion , biochemistry , membrane , biology , receptor , organic chemistry
Uncoupling proteins (UCP) are known to transport anions, such as Cl − , in addition to H + transport. Although H + transport by UCP is clearly involved in thermogenesis, the mechanism of its anion transport is not clearly understood. In this study, we examined the anion channel characteristics of the six individual helical transmembrane (TM) domains of the human UCP2. The second TM domain peptide (TM2) forms multi‐state channels by assemblies of conductive oligomers. Furthermore, the TM2 exhibited voltage‐dependent anion channels with properties comparable to those of UCP1 chloride channel. However, the other five TM peptides did not form UCP1‐like channels. Moreover, an analog of TM2 in which two Arg residues were substituted by Ala residues did not form stable channels, implying the significance of Arg residues for anion transport. These results suggest that the anion channel structure of UCP2 protein is oligomeric and the second TM domain is essential for the voltage‐dependence of this anion channel.