The targeting information of the mitochondrial outer membrane isoform of cytochrome <i>b</i>5 is contained within the carboxyl‐terminal region

Silvestris, Marcella De; D’Arrigo, Antonello; Borgese, Nica

doi:10.1016/0014-5793(95)00797-d

Cited by 49 publications

(44 citation statements)

References 23 publications

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“…The open reading frame starting from the putative ATG initiation codon codes for a peptide consisting of 146 amino acid residues, and the deduced amino acid sequence coincides with that obtained from direct amino acid sequencing of the purified tryptic cytochrome (14) and partial cDNA cloning (15), except for an additional 12 amino acid residues (Met-Ala-Thr-Pro-Glu-Ala-Ser-Gly-Ser-Gly-Arg-Asn) present at the amino-terminal end. The protein has no typical structural feature, i.e.…”

Section: Cdna Cloning and The Deduced Amino Acid Sequence Of Ratmentioning

confidence: 77%

“…The amino-terminal domain has about 100 amino acid residues, contains a protoheme, extends out of the membrane, and participates in electron-transferring functions (4,5,13). Sequences of this domain of cyt b 5 and OMb are about 70% identical (14,15). The hydrophobic domain consisting of about 20 amino acid residues is embedded in the lipid bilayer and functions for the insertion of proteins into the membranes as tail-anchored proteins (16).…”

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confidence: 99%

“…A long stretch of uncharged amino acid residues with the intervention of positively charged amino acids, which is a typical structural feature common to the mitochondrial targeting signal, was not found in the amino-terminal amino acid sequence obtained from the direct sequencing of the purified tryptic cytochrome and partial cDNA cloning (14,15,20). It has been reported that the carboxyl-terminal 43 amino acids of OMb contain sufficient information to target the cytochrome to the mitochondria (15).…”

mentioning

confidence: 99%

“…It has been reported that the carboxyl-terminal 43 amino acids of OMb contain sufficient information to target the cytochrome to the mitochondria (15). However, such a long stretch of the amino acid sequence, which is about one-third of the entire protein, may not be needed as the targeting signal.…”

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confidence: 99%

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Charged Amino Acids at the Carboxyl-Terminal Portions Determine the Intracellular Locations of Two Isoforms of Cytochromeb 5

Kuroda

Ikenoue

Honsho

et al. 1998

Journal of Biological Chemistry

108

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Outer mitochondrial membrane cytochrome b 5 (OMb), which is an isoform of cytochrome b 5 (cyt b 5 ) 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 b 5 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 amino acids by alanine resulted in the transport of the mutant proteins to the endoplasmic reticulum. The mutant cyt b 5 , in which the acidic amino acid in its carboxyl-terminal end was replaced by basic amino acid, could be transported to the mitochondria. It would thus seem that charged amino acids in the carboxylterminal portion of these proteins determine their locations in the cell.

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Section: Cdna Cloning and The Deduced Amino Acid Sequence Of Ratmentioning

confidence: 77%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Charged Amino Acids at the Carboxyl-Terminal Portions Determine the Intracellular Locations of Two Isoforms of Cytochromeb 5

Kuroda

Ikenoue

Honsho

et al. 1998

Journal of Biological Chemistry

108

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“…In addition to the ER, members of this unique class of membrane proteins are found in several other organelles including various post-ER compartments within the secretory pathway (e.g. Golgi, vacuoles, and synaptic vesicles) (38 -42), mitochondria (43)(44)(45)(46), and peroxisomes (15,19). For all tail-anchored proteins examined to date, the initial membrane-targeting event is mediated by sequences within the C-terminal region of the protein.…”

Section: Discussionmentioning

confidence: 99%

The Sorting Signals for Peroxisomal Membrane-bound Ascorbate Peroxidase Are within Its C-terminal Tail

Mullen

Trelease

2000

Journal of Biological Chemistry

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Peroxisomal ascorbate peroxidase (APX) is a carboxyl tail-anchored, type II (N cytosol -C matrix ) integral membrane protein that functions in the regeneration of NAD ؉ in glyoxysomes of germinated oilseeds and protection of peroxisomes in other organisms from toxic H 2 O 2 . Recently we showed that cottonseed peroxisomal APX was sorted post-translationally from the cytosol to peroxisomes via a novel reticular/circular membranous network that was interpreted to be a subdomain of the endoplasmic reticulum (ER), named peroxisomal ER (pER). Here we report on the molecular signals responsible for sorting peroxisomal APX. Deletions or site-specific substitutions of certain amino acid residues within the hydrophilic C-terminal-most eight-amino acid residues (includes a positively charged domain found in most peroxisomal integral membrane-destined proteins) abolished sorting of peroxisomal APX to peroxisomes via pER. However, the C-terminal tail was not sufficient for sorting chloramphenicol acetyltransferase to peroxisomes via pER, whereas the peptide plus most of the immediately adjacent 21-amino acid transmembrane domain (TMD) of peroxisomal APX was sufficient for sorting. Replacement of the peroxisomal APX TMD with an artificial TMD (devoid of putative sorting sequences) plus the peroxisomal APX C-terminal tail also sorted chloramphenicol acetyltransferase to peroxisomes via pER, indicating that the peroxisomal APX TMD does not possess essential sorting information. Instead, the TMD appears to confer the proper context required for the conserved positively charged domain to function within peroxisomal APX as an overlapping pER sorting signal and a membrane peroxisome targeting signal type 2.Peroxisomes are single membrane-bound organelles that do not contain DNA nor protein-synthesizing machinery. Data published thus far indicate that they acquire their nuclearencoded matrix and boundary membrane protein constituents from the cytosol in a regulated, post-translational manner. For instance, proteins destined for the peroxisomal matrix are sorted by at least two evolutionarily conserved targeting signals, the type 1 and type 2 peroxisomal targeting signal (PTS).

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Molecular dynamics simulation studies of cytochrome b₅ from outer mitochondrial and microsomal membrane

Lee

Kuczera

2003

Biopolymers

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Two forms of cytochrome b(5) have been identified, associated with the outer membrane of liver mitochondria (OM cyt b(5)) and with the membrane of the endoplasmic reticulum (microsomal, Mc cyt b(5)). These proteins have very similar structures, but differ significantly in physical properties, with the OM cyt b(5) exhibiting a more negative reduction potential, higher stability, and stronger interactions with the heme. We perform molecular dynamics simulations to probe the structures and fluctuations of the two proteins in solution, to help explain the observed physical differences. We find that the structures of the two proteins, highly similar in the crystal, differ in position of a surface loop involving residues 49-51 in solution. Hydrophobic residues Ala-18, Ile-32, Leu-36, and Leu-47 tend to cluster together on the surface of rat OM cyt b(5), blocking water access to the protein interior. In bovine Mc cyt b(5), two of these positions, Ser-18 and Arg-47, are occupied by hydrophilic residues. This leads to breaking the hydrophobic cluster and allowing the protein to occupy a more open conformation. A measure of this structural transition is the opening of a cleft on the protein surface, which is 5 A wider in the OM cyt b(5) simulation compared to the Mc form. The OM protein also appears to have a more compact hydrophobic core in its beta-sheet region. These effects may be used to explain observed stability differences between the two proteins.

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The targeting information of the mitochondrial outer membrane isoform of cytochrome b5 is contained within the carboxyl‐terminal region

Cited by 49 publications

References 23 publications

Charged Amino Acids at the Carboxyl-Terminal Portions Determine the Intracellular Locations of Two Isoforms of Cytochromeb 5

Charged Amino Acids at the Carboxyl-Terminal Portions Determine the Intracellular Locations of Two Isoforms of Cytochromeb 5

The Sorting Signals for Peroxisomal Membrane-bound Ascorbate Peroxidase Are within Its C-terminal Tail

Molecular dynamics simulation studies of cytochrome b₅ from outer mitochondrial and microsomal membrane

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The targeting information of the mitochondrial outer membrane isoform of cytochrome b5 is contained within the carboxyl‐terminal region

Cited by 49 publications

References 23 publications

Charged Amino Acids at the Carboxyl-Terminal Portions Determine the Intracellular Locations of Two Isoforms of Cytochromeb 5

Charged Amino Acids at the Carboxyl-Terminal Portions Determine the Intracellular Locations of Two Isoforms of Cytochromeb 5

The Sorting Signals for Peroxisomal Membrane-bound Ascorbate Peroxidase Are within Its C-terminal Tail

Molecular dynamics simulation studies of cytochrome b5 from outer mitochondrial and microsomal membrane

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Molecular dynamics simulation studies of cytochrome b₅ from outer mitochondrial and microsomal membrane