TY - JOUR
T1 - Charged amine acids at the carboxyl-terminal portions determine the intracellular locations of two isoforms of cytochrome b5
AU - Kuroda, Rieko
AU - Ikenoue, Takao
AU - Honsho, Masanori
AU - Tsujimoto, Shoko
AU - Mitoma, Jun Ya
AU - Ito, Akio
N1 - Copyright:
Copyright 2004 Elsevier Science B.V., Amsterdam. All rights reserved.
PY - 1998/11/20
Y1 - 1998/11/20
N2 - Outer mitochondrial membrane cytochrome b5 (OMb), which is an isoform of cytochrome b5 (cyt b5) in the endoplasmic reticulum, is a typical tail- anchored protein of the outer mitochondrial membrane. We cloned cDNA containing the complete amino acid sequence of OMb and found that the protein has no typical structural feature common to the mitochondrial targeting signal at the amino terminus. To identify the region responsible for the mitochondrial targeting of OMb, various mutated proteins were expressed in cultured mammalian cells, and the subcellular localization of the expressed proteins was analyzed. The deletion of more than 11 amino acid residues from the carboxyl-terminal end of OMb abolished the targeting of the protein to the mitochondria. When the carboxyl-terminal 10 amino acids of OMb were fused to the cyt b5 that was previously deleted in the corresponding 10 residues, the fused protein localized in the mitochondria, thereby indicating that the carboxyl-terminal 10 amino acid residues of OMb have sufficient information to transport OMb to the mitochondria. The replacement of either of the two positively charged residues within the carboxyl-terminal 10 amine acids by alanine resulted in the transport of the mutant proteins to the endoplasmic reticulum. The mutant cyt b5, in which the acidic amine acid in its carboxyl-terminal end was replaced by basic amine acid, could be transported to the mitochondria. It would thus seem that charged amine acids in the carboxyl-terminal portion of these proteins determine their locations in the cell.
AB - Outer mitochondrial membrane cytochrome b5 (OMb), which is an isoform of cytochrome b5 (cyt b5) in the endoplasmic reticulum, is a typical tail- anchored protein of the outer mitochondrial membrane. We cloned cDNA containing the complete amino acid sequence of OMb and found that the protein has no typical structural feature common to the mitochondrial targeting signal at the amino terminus. To identify the region responsible for the mitochondrial targeting of OMb, various mutated proteins were expressed in cultured mammalian cells, and the subcellular localization of the expressed proteins was analyzed. The deletion of more than 11 amino acid residues from the carboxyl-terminal end of OMb abolished the targeting of the protein to the mitochondria. When the carboxyl-terminal 10 amino acids of OMb were fused to the cyt b5 that was previously deleted in the corresponding 10 residues, the fused protein localized in the mitochondria, thereby indicating that the carboxyl-terminal 10 amino acid residues of OMb have sufficient information to transport OMb to the mitochondria. The replacement of either of the two positively charged residues within the carboxyl-terminal 10 amine acids by alanine resulted in the transport of the mutant proteins to the endoplasmic reticulum. The mutant cyt b5, in which the acidic amine acid in its carboxyl-terminal end was replaced by basic amine acid, could be transported to the mitochondria. It would thus seem that charged amine acids in the carboxyl-terminal portion of these proteins determine their locations in the cell.
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U2 - 10.1074/jbc.273.47.31097
DO - 10.1074/jbc.273.47.31097
M3 - Article
C2 - 9813010
AN - SCOPUS:0032553126
VL - 273
SP - 31097
EP - 31102
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 47
ER -