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Regulated and unregulated mitochondrial permeability transition pores: a new paradigm of pore structure and function?
Author(s) -
He Lihua,
Lemasters John J
Publication year - 2002
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/s0014-5793(01)03314-2
Subject(s) - mitochondrial permeability transition pore , permeability (electromagnetism) , biophysics , chemistry , function (biology) , chemical physics , chemical engineering , microbiology and biotechnology , biochemistry , biology , engineering , apoptosis , membrane , programmed cell death
Cyclosporin A (CsA) inhibits the mitochondrial permeability transition (MPT), but not always. To characterize the CsA‐sensitive and ‐insensitive MPT, rat liver mitochondria were exposed to low and high doses of various MPT inducers. Mitochondrial swelling, cyclophilin D membrane binding and permeability transition (PT) pore diameter were measured. The results indicate two conductance modes for the PT pore: one activated by Ca 2+ and inhibited by CsA and Mg 2+ and the other unregulated. We propose a new model of pore formation and gating in which PT pores form by aggregation of misfolded integral membrane proteins damaged by oxidant and other stresses. Chaperone‐like proteins initially block conductance through these misfolded protein clusters; however, increased Ca 2+ opens these regulated PT pores, an effect blocked by CsA. When protein clusters exceed chaperones available to block conductance, unregulated pore opening occurs.