PXA2

UniProt ID: P34230
Organism: Saccharomyces cerevisiae S288C
Review Status: COMPLETE
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Gene Description

PXA2 (also PAT1) encodes one of the two peroxisomal ABC half-transporters of S. cerevisiae. Pxa1p and Pxa2p are the two half ATP-binding-cassette transporters of the ABCD (ALDP/PMP70) family in the S. cerevisiae peroxisomal membrane; they heterodimerise to form a full transporter that imports long-chain and very long-chain acyl groups from the cytosolic acyl-CoA pool into the peroxisome, the only site of fatty acid beta-oxidation in yeast. The complex hydrolyses the acyl-CoA during transport and translocates the fatty acid moiety, which is re-esterified to CoA on the luminal side by the acyl-CoA synthetases Faa2p and/or Fat1p; medium-chain fatty acids instead enter as free acids and are activated by Faa2p. pxa mutants fail to oxidise oleate and other long-chain fatty acids and grow poorly on oleate, but have normal peroxisomes. The pxa1 pxa2 defect is partly complemented by human ABCD1 or ABCD2 acting as homodimers. Pxa1p-Pxa2p also mediates unidirectional ATP uptake into peroxisomes, alongside the Ant1p and Aac2p nucleotide carriers. The C-terminal region of Pxa2p is required for its interaction with Pxa1p.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0005324 long-chain fatty acid transmembrane transporter activity
IBA
GO_REF:0000033
ACCEPT
Summary: PAINT IBA for long-chain fatty acid transmembrane transporter activity (ABCD1/ABCD2 clade, yeast PXA1/PXA2 among sources). Consistent with the mechanism in which the Pxa1p-Pxa2p complex hydrolyses (very) long-chain acyl-CoA and translocates the fatty acid moiety.
Supporting Evidence:
PMID:22493507
very long chain acyl-CoA esters are hydrolyzed by the Pxa1p-Pxa2p complex prior to the actual transport of their fatty acid moiety into the peroxisomes
PMID:8670886
long-chain fatty acids are imported from the cytosolic pool of activated long-chain fatty acids via Pat1p and Pat2p, peroxisomal membrane proteins belonging to the ATP binding cassette transporter superfamily.
GO:0005324 long-chain fatty acid transmembrane transporter activity
IEA
GO_REF:0000002
ACCEPT
Summary: InterPro2GO (IPR005283, ABCD family) mapping to long-chain fatty acid transmembrane transporter activity. Correct for the yeast heterodimer.
Supporting Evidence:
PMID:22493507
very long chain acyl-CoA esters are hydrolyzed by the Pxa1p-Pxa2p complex prior to the actual transport of their fatty acid moiety into the peroxisomes
GO:0005324 long-chain fatty acid transmembrane transporter activity
IGI
PMID:18757502
The human peroxisomal ABC half transporter ALDP functions as...
ACCEPT
Summary: The pxa1/pxa2 deletion phenotype is partially rescued by human ABCD1 (with/from), and the yeast heterodimer handles a spectrum of acyl-CoA esters. Supports long-chain fatty acyl import; whether the translocated species is acyl-CoA or free fatty acid was later resolved in favour of hydrolysis followed by fatty acid transport (PMID:22493507).
Supporting Evidence:
PMID:18757502
we show that the Pxa1p/Pxa2p heterodimer is involved in the transport of a spectrum of acyl-CoA esters.
PMID:18757502
the mutant phenotype of the pxa1/pxa2Delta mutant can be rescued, at least partially, by the sole expression of the human ABCD1 cDNA
PMID:22493507
very long chain acyl-CoA esters are hydrolyzed by the Pxa1p-Pxa2p complex prior to the actual transport of their fatty acid moiety into the peroxisomes
GO:0005515 protein binding
IPI
PMID:23831759
Mapping the functional yeast ABC transporter interactome.
REMOVE
Summary: Membrane yeast two-hybrid (MYTH) interactome screen of yeast ABC transporters reported PXA2p interactions with unrelated soluble proteins (e.g. Arf1p and others). 'Protein binding' is uninformative and these high-throughput hits have no established functional significance for the transporter.
Reason: Uninformative 'protein binding' from a high-throughput MYTH screen with no functional follow-up; removal does not imply the interaction is false.
GO:0005515 protein binding
IPI
PMID:23831759
Mapping the functional yeast ABC transporter interactome.
REMOVE
Summary: Membrane yeast two-hybrid (MYTH) interactome screen of yeast ABC transporters reported PXA2p interactions with unrelated soluble proteins (e.g. Arf1p and others). 'Protein binding' is uninformative and these high-throughput hits have no established functional significance for the transporter.
Reason: Uninformative 'protein binding' from a high-throughput MYTH screen with no functional follow-up; removal does not imply the interaction is false.
GO:0005515 protein binding
IPI
PMID:23831759
Mapping the functional yeast ABC transporter interactome.
REMOVE
Summary: Membrane yeast two-hybrid (MYTH) interactome screen of yeast ABC transporters reported PXA2p interactions with unrelated soluble proteins (e.g. Arf1p and others). 'Protein binding' is uninformative and these high-throughput hits have no established functional significance for the transporter.
Reason: Uninformative 'protein binding' from a high-throughput MYTH screen with no functional follow-up; removal does not imply the interaction is false.
GO:0005515 protein binding
IPI
PMID:23831759
Mapping the functional yeast ABC transporter interactome.
REMOVE
Summary: Membrane yeast two-hybrid (MYTH) interactome screen of yeast ABC transporters reported PXA2p interactions with unrelated soluble proteins (e.g. Arf1p and others). 'Protein binding' is uninformative and these high-throughput hits have no established functional significance for the transporter.
Reason: Uninformative 'protein binding' from a high-throughput MYTH screen with no functional follow-up; removal does not imply the interaction is false.
GO:0005515 protein binding
IPI
PMID:8876235
A Saccharomyces cerevisiae homolog of the human adrenoleukod...
MODIFY
Summary: Co-immunoprecipitation of Pxa1p with Pxa2p: the two half-transporters form the functional heterodimeric ABC transporter. The interaction is real and important, but is better represented by membership of the ABC transporter complex (GO:0043190, also annotated) than by 'protein binding'.
Reason: Biologically meaningful heterodimerisation with PXA1; 'protein binding' itself is uninformative, and the complex annotation captures it.
Supporting Evidence:
PMID:8876235
Finally, we find that Pxa1p and Pxa2p coimmuno-precipitate.
PMID:8876235
These genetic and physical data suggest that Pxa1p and Pxa2p heterodimerize to form a complete peroxisomal ABC transporter involved in fatty acid beta-oxidation.
GO:0005524 ATP binding
IBA
GO_REF:0000033
KEEP AS NON CORE
Summary: PAINT IBA for ATP binding by the nucleotide-binding domain. Correct, but part of the transporter's ATPase cycle rather than a separate function.
Reason: Implicit in ATP-driven transport.
Supporting Evidence:
file:yeast/PXA2/PXA2-uniprot.txt
Belongs to the ABC transporter superfamily. ABCD family.
GO:0005524 ATP binding
IEA
GO_REF:0000002
KEEP AS NON CORE
Summary: InterPro2GO (ABC transporter-like/ABCD) mapping to ATP binding. Correct but implicit in transporter activity.
Reason: Implicit in ATP-driven transport.
Supporting Evidence:
file:yeast/PXA2/PXA2-uniprot.txt
Belongs to the ABC transporter superfamily. ABCD family.
GO:0005777 peroxisome
IDA
PMID:27663510
Characterization of proteome dynamics during growth in oleat...
ACCEPT
Summary: High-content localisation screens during oleate growth visualised GFP-Pxa2 in peroxisomes.
Supporting Evidence:
PMID:27663510
the constitutively expressed GFP-Pxa2 could be visualized in peroxisomes in both conditions
GO:0005777 peroxisome
IEA
GO_REF:0000120
ACCEPT
Summary: Combined IEA (ARBA/InterPro) mapping to peroxisome. Correct; the more specific peroxisomal membrane is also annotated.
Supporting Evidence:
file:yeast/PXA2/PXA2-uniprot.txt
SUBCELLULAR LOCATION: Peroxisome membrane; Multi-pass membrane protein.
GO:0005778 peroxisomal membrane
IBA
GO_REF:0000033
ACCEPT
Summary: PAINT IBA for peroxisomal-membrane activity of the ABCD family. Correct; Pxa2p is an integral peroxisomal-membrane half-transporter.
Supporting Evidence:
file:yeast/PXA2/PXA2-uniprot.txt
SUBCELLULAR LOCATION: Peroxisome membrane; Multi-pass membrane protein.
PMID:8670886
long-chain fatty acids are imported from the cytosolic pool of activated long-chain fatty acids via Pat1p and Pat2p, peroxisomal membrane proteins belonging to the ATP binding cassette transporter superfamily.
GO:0005778 peroxisomal membrane
IDA
PMID:35127709
Peroxisomal ATP Uptake Is Provided by Two Adenine Nucleotide...
ACCEPT
Summary: Peroxisomal-membrane proteoliposome and reporter experiments place Pxa1p/Pxa2p activity in the peroxisomal membrane.
Supporting Evidence:
PMID:35127709
the ABC transporter protein complex Pxa1p/Pxa2p, which mediates both uni-directional acyl-CoA and ATP uptake
GO:0005778 peroxisomal membrane
IDA
PMID:9395310
Transport of activated fatty acids by the peroxisomal ATP-bi...
ACCEPT
Summary: Semi-intact cell assays show Pxa2p-dependent import of C18:1-CoA into peroxisomes, consistent with Pxa2p in the peroxisomal membrane.
Supporting Evidence:
PMID:9395310
we show that C18:1-CoA, but not C8:0-CoA, enters the peroxisome via Pxa2p, in an ATP-dependent fashion.
file:yeast/PXA2/PXA2-uniprot.txt
SUBCELLULAR LOCATION: Peroxisome membrane; Multi-pass membrane protein.
GO:0005778 peroxisomal membrane
IEA
GO_REF:0000044
ACCEPT
Summary: UniProt subcellular-location mapping to peroxisomal membrane. Correct.
Supporting Evidence:
file:yeast/PXA2/PXA2-uniprot.txt
SUBCELLULAR LOCATION: Peroxisome membrane; Multi-pass membrane protein.
GO:0005778 peroxisomal membrane
NAS
PMID:22493507
Peroxisomal fatty acid uptake mechanism in Saccharomyces cer...
ACCEPT
Summary: Statement in van Roermund et al. 2012 about the Pxa1p-Pxa2p complex in the peroxisomal membrane. Correct and corroborated by experimental data.
Supporting Evidence:
PMID:22493507
The Pxa1p-Pxa2p complex functionally interacts with the acyl-CoA synthetases Faa2p and/or Fat1p on the inner surface of the peroxisomal membrane
file:yeast/PXA2/PXA2-uniprot.txt
SUBCELLULAR LOCATION: Peroxisome membrane; Multi-pass membrane protein.
GO:0006635 fatty acid beta-oxidation
IBA
GO_REF:0000033
ACCEPT
Summary: PAINT IBA for fatty acid beta-oxidation. The transporter delivers long-chain acyl substrates into the peroxisome, the exclusive site of beta-oxidation in yeast; pxa mutants are deficient in oleate oxidation. Accepted as the pathway the transport step serves.
Supporting Evidence:
PMID:8876235
These genetic and physical data suggest that Pxa1p and Pxa2p heterodimerize to form a complete peroxisomal ABC transporter involved in fatty acid beta-oxidation.
PMID:21145416
the phenotype of the pxa1/pxa2Ξ” yeast mutant, i.e. impaired growth on oleate containing medium and deficient oxidation of oleic acid, cannot only be partially rescued by human ABCD1, but also by human ABCD2 (ALDRP)
GO:0006635 fatty acid beta-oxidation
IGI
PMID:18757502
The human peroxisomal ABC half transporter ALDP functions as...
ACCEPT
Summary: Genetic interaction data (with FAA2 and the partner half-transporter) linking Pxa1p/Pxa2p-mediated uptake to peroxisomal beta-oxidation of long-chain substrates.
Supporting Evidence:
PMID:18757502
we show that the Pxa1p/Pxa2p heterodimer is involved in the transport of a spectrum of acyl-CoA esters.
GO:0007031 peroxisome organization
IBA
GO_REF:0000033
REMOVE
Summary: PAINT IBA for peroxisome organization, seeded from human ABCD1/ABCD3. For yeast, Shani & Valle showed Pxa1p and Pxa2p are associated with peroxisomes but not required for their assembly; the transporter acts on substrate import, not organelle biogenesis.
Reason: Contradicted for the yeast proteins: neither PXA1 nor PXA2 is required for peroxisome assembly. Over-propagation from mammalian ABCD members.
Propagation Review
Root cause: PROPAGATION BAD
Failure modes: FUNCTIONAL DIVERGENCE
Sources checked:
UniProtKB:P28288 Β· ABCD3 (PMP70), human SUPPORTS SOURCE BUT NOT TARGET
Mammalian ABCD source; the yeast Pxa1p/Pxa2p half-transporters are not required for peroxisome assembly (PMID:8876235).
UniProtKB:P33897 Β· ABCD1 (ALDP), human SUPPORTS SOURCE BUT NOT TARGET
Mammalian ABCD source; organelle-biogenesis role not transferable to the yeast heterodimer.
Supporting Evidence:
PMID:8876235
is associated with peroxisomes but not required for their assembly.
GO:0015867 ATP transport
IDA
PMID:35127709
Peroxisomal ATP Uptake Is Provided by Two Adenine Nucleotide...
KEEP AS NON CORE
Summary: van Roermund et al. 2022 found that, besides Ant1p and Aac2p, the Pxa1p/Pxa2p complex mediates unidirectional ATP uptake into peroxisomes (proteoliposome assays and peroxisomal ATP sensors). A genuine but secondary activity relative to acyl-CoA import.
Reason: Experimentally supported secondary transport activity; acyl import is the primary function.
Supporting Evidence:
PMID:35127709
These findings pointed to a novel, unanticipated role for the ABC transporter protein complex Pxa1p/Pxa2p in peroxisomal ATP uptake in addition to its established role in the peroxisomal import of fatty acyl-CoAs.
GO:0015910 long-chain fatty acid import into peroxisome
IBA
GO_REF:0000033
ACCEPT
Summary: PAINT IBA for long-chain fatty acid import into peroxisome. This is the core process of Pxa1p-Pxa2p.
Supporting Evidence:
PMID:8670886
long-chain fatty acids are imported from the cytosolic pool of activated long-chain fatty acids via Pat1p and Pat2p, peroxisomal membrane proteins belonging to the ATP binding cassette transporter superfamily.
PMID:22493507
very long chain acyl-CoA esters are hydrolyzed by the Pxa1p-Pxa2p complex prior to the actual transport of their fatty acid moiety into the peroxisomes
GO:0015910 long-chain fatty acid import into peroxisome
IDA
PMID:25118695
Involvement of the carboxyl-terminal region of the yeast per...
ACCEPT
Summary: Chuang et al. showed that the Pxa2p C-terminal region mediates interaction with Pxa1p and is required for transporter function, assayed by growth on oleate. Supports the role of the heterodimer in long-chain fatty acid import.
Supporting Evidence:
PMID:25118695
The oleate plate functional assay clearly demonstrated that the CT2 of Pxa2p is required for transporter function, suggesting that the interactions identified here are functionally related.
GO:0015910 long-chain fatty acid import into peroxisome
IEA
GO_REF:0000002
ACCEPT
Summary: InterPro2GO (ABCD family) mapping to long-chain fatty acid import into peroxisome. Correct.
Supporting Evidence:
PMID:8670886
long-chain fatty acids are imported from the cytosolic pool of activated long-chain fatty acids via Pat1p and Pat2p, peroxisomal membrane proteins belonging to the ATP binding cassette transporter superfamily.
GO:0015910 long-chain fatty acid import into peroxisome
IGI
PMID:18757502
The human peroxisomal ABC half transporter ALDP functions as...
ACCEPT
Summary: Rescue of pxa1/pxa2 deletion by human ABCD1 supports the conserved role in import of long-chain acyl groups into peroxisomes.
Supporting Evidence:
PMID:18757502
we show that the Pxa1p/Pxa2p heterodimer is involved in the transport of a spectrum of acyl-CoA esters.
PMID:18757502
the mutant phenotype of the pxa1/pxa2Delta mutant can be rescued, at least partially, by the sole expression of the human ABCD1 cDNA
GO:0015916 fatty-acyl-CoA transport
IGI
PMID:18757502
The human peroxisomal ABC half transporter ALDP functions as...
KEEP AS NON CORE
Summary: van Roermund et al. 2008 concluded that the heterodimer transports acyl-CoA esters. The same group later showed the acyl-CoA is hydrolysed by the complex and only the fatty acid moiety is translocated, so 'fatty-acyl-CoA transport' describes the substrate taken up from the cytosol but not the translocated species.
Reason: Accurately reflects acyl-CoA as the cytosolic substrate, but the mechanistic picture (PMID:22493507) favours fatty acid translocation; the core process is GO:0015910.
Supporting Evidence:
PMID:18757502
we show that the Pxa1p/Pxa2p heterodimer is involved in the transport of a spectrum of acyl-CoA esters.
PMID:22493507
very long chain acyl-CoA esters are hydrolyzed by the Pxa1p-Pxa2p complex prior to the actual transport of their fatty acid moiety into the peroxisomes
GO:0016020 membrane
IEA
GO_REF:0000120
TOO GENERAL
Summary: Generic 'membrane' from combined IEA. Correct but uninformative; the specific location is the peroxisomal membrane.
Reason: Generic ancestor of GO:0005778.
Supporting Evidence:
file:yeast/PXA2/PXA2-uniprot.txt
SUBCELLULAR LOCATION: Peroxisome membrane; Multi-pass membrane protein.
GO:0016887 ATP hydrolysis activity
IEA
GO_REF:0000002
KEEP AS NON CORE
Summary: InterPro2GO (ABC transporter-like) mapping to ATP hydrolysis activity. The NBDs hydrolyse ATP to drive transport; this is a component of the transporter activity rather than a stand-alone function.
Reason: Part of the ATPase-coupled transport mechanism.
Supporting Evidence:
PMID:9395310
we show that C18:1-CoA, but not C8:0-CoA, enters the peroxisome via Pxa2p, in an ATP-dependent fashion.
GO:0042626 ATPase-coupled transmembrane transporter activity
IBA
GO_REF:0000033
TOO GENERAL
Summary: PAINT IBA for ATPase-coupled transmembrane transporter activity of ABCD transporters. Correct but generic; PXA2, as half of the Pxa1p-Pxa2p heterodimer, mediates ATP-dependent import of long-chain acyl groups.
Supporting Evidence:
PMID:9395310
we show that C18:1-CoA, but not C8:0-CoA, enters the peroxisome via Pxa2p, in an ATP-dependent fashion.
PMID:8876235
These genetic and physical data suggest that Pxa1p and Pxa2p heterodimerize to form a complete peroxisomal ABC transporter involved in fatty acid beta-oxidation.
GO:0042626 ATPase-coupled transmembrane transporter activity
IDA
PMID:35127709
Peroxisomal ATP Uptake Is Provided by Two Adenine Nucleotide...
TOO GENERAL
Summary: ATP-dependent transport by Pxa1p/Pxa2p shown in proteoliposomes from peroxisomal membranes. Correct, if generic.
Supporting Evidence:
PMID:35127709
the ABC transporter protein complex Pxa1p/Pxa2p, which mediates both uni-directional acyl-CoA and ATP uptake
GO:0042626 ATPase-coupled transmembrane transporter activity
IDA
PMID:9395310
Transport of activated fatty acids by the peroxisomal ATP-bi...
TOO GENERAL
Summary: In digitonin-permeabilised cells C18:1-CoA enters peroxisomes via Pxa2p in an ATP-dependent manner: direct support for ATP-coupled transport.
Supporting Evidence:
PMID:9395310
we show that C18:1-CoA, but not C8:0-CoA, enters the peroxisome via Pxa2p, in an ATP-dependent fashion.
GO:0042626 ATPase-coupled transmembrane transporter activity
IEA
GO_REF:0000002
TOO GENERAL
Summary: InterPro2GO (ABCD family) mapping to ATPase-coupled transmembrane transporter activity. Correct but generic.
Supporting Evidence:
PMID:9395310
we show that C18:1-CoA, but not C8:0-CoA, enters the peroxisome via Pxa2p, in an ATP-dependent fashion.
GO:0042758 long-chain fatty acid catabolic process
IMP
PMID:18757502
The human peroxisomal ABC half transporter ALDP functions as...
ACCEPT
Summary: pxa mutants are deficient in oxidation of long-chain fatty acids such as oleate. The transporter supplies substrate to peroxisomal beta-oxidation.
Supporting Evidence:
PMID:18757502
we show that the Pxa1p/Pxa2p heterodimer is involved in the transport of a spectrum of acyl-CoA esters.
PMID:21145416
the phenotype of the pxa1/pxa2Ξ” yeast mutant, i.e. impaired growth on oleate containing medium and deficient oxidation of oleic acid, cannot only be partially rescued by human ABCD1, but also by human ABCD2 (ALDRP)
GO:0042760 very long-chain fatty acid catabolic process
IBA
GO_REF:0000033
ACCEPT
Summary: PAINT IBA for very long-chain fatty acid catabolic process (ABCD1/ABCD2 clade). Consistent with Pxa1p-Pxa2p handling very long-chain acyl-CoA esters.
Supporting Evidence:
PMID:22493507
very long chain acyl-CoA esters are hydrolyzed by the Pxa1p-Pxa2p complex prior to the actual transport of their fatty acid moiety into the peroxisomes
GO:0042760 very long-chain fatty acid catabolic process
IGI
PMID:21145416
Differential substrate specificities of human ABCD1 and ABCD...
ACCEPT
Summary: Very long-chain fatty acid oxidation in the pxa1/pxa2 double mutant depends on Pxa1p-Pxa2p and is restored by human ABCD1/ABCD2 (with/from: PXA1).
Supporting Evidence:
PMID:21145416
the phenotype of the pxa1/pxa2Ξ” yeast mutant, i.e. impaired growth on oleate containing medium and deficient oxidation of oleic acid, cannot only be partially rescued by human ABCD1, but also by human ABCD2 (ALDRP)
PMID:21145416
full rescue of beta-oxidation activity in cells expressing human ABCD2 was observed with C22:0 and different unsaturated very long-chain fatty acids including C24:6 and especially C22:6 whereas in cells expressing HsABCD1 rescue of beta-oxidation activity was best with C24:0 and C26:0 as substrates.
GO:0042760 very long-chain fatty acid catabolic process
IMP
PMID:18757502
The human peroxisomal ABC half transporter ALDP functions as...
ACCEPT
Summary: pxa mutants have defective handling of very long-chain acyl-CoAs; consistent with the ABCD-family role in VLCFA delivery to peroxisomal beta-oxidation.
Supporting Evidence:
PMID:18757502
we show that the Pxa1p/Pxa2p heterodimer is involved in the transport of a spectrum of acyl-CoA esters.
GO:0043190 ATP-binding cassette (ABC) transporter complex
IPI
PMID:25118695
Involvement of the carboxyl-terminal region of the yeast per...
ACCEPT
Summary: Two-hybrid mapping of the Pxa1p-Pxa2p interaction (Pxa2p C-terminus required) supports Pxa1p and Pxa2p forming a heterodimeric ABC transporter complex.
Supporting Evidence:
PMID:25118695
Using a yeast two-hybrid assay, we found that the carboxyl-terminal region (CT) of Pxa2p, but not of Pxa1p, is required for their interaction.
PMID:8876235
These genetic and physical data suggest that Pxa1p and Pxa2p heterodimerize to form a complete peroxisomal ABC transporter involved in fatty acid beta-oxidation.
GO:0055085 transmembrane transport
IEA
GO_REF:0000002
TOO GENERAL
Summary: InterPro2GO (ABC transmembrane domain) mapping to generic transmembrane transport. Correct but uninformative; the specific process is long-chain fatty acid import into peroxisome.
Reason: Generic ancestor of GO:0015910.
Supporting Evidence:
PMID:8670886
long-chain fatty acids are imported from the cytosolic pool of activated long-chain fatty acids via Pat1p and Pat2p, peroxisomal membrane proteins belonging to the ATP binding cassette transporter superfamily.
GO:0140359 ABC-type transporter activity
IEA
GO_REF:0000002
ACCEPT
Summary: InterPro2GO mapping to ABC-type transporter activity. Correct description of the transporter class.
Supporting Evidence:
file:yeast/PXA2/PXA2-uniprot.txt
Belongs to the ABC transporter superfamily. ABCD family.
PMID:8876235
These genetic and physical data suggest that Pxa1p and Pxa2p heterodimerize to form a complete peroxisomal ABC transporter involved in fatty acid beta-oxidation.
GO:1902001 fatty acid transmembrane transport
IDA
PMID:9395310
Transport of activated fatty acids by the peroxisomal ATP-bi...
ACCEPT
Summary: Pxa2p-dependent, ATP-dependent uptake of long-chain (C18:1) but not medium-chain acyl-CoA into peroxisomes. Correct; GO:0015910 is the more specific peroxisomal term.
Supporting Evidence:
PMID:9395310
we show that C18:1-CoA, but not C8:0-CoA, enters the peroxisome via Pxa2p, in an ATP-dependent fashion.

Core Functions

Half-transporter subunit of the heterodimeric Pxa1p-Pxa2p ABCD transporter in the peroxisomal membrane that imports long-chain/very-long-chain acyl groups from cytosolic acyl-CoA (hydrolysed during transport, translocating the fatty acid) for peroxisomal beta-oxidation.

Supporting Evidence:
  • PMID:8670886
    long-chain fatty acids are imported from the cytosolic pool of activated long-chain fatty acids via Pat1p and Pat2p, peroxisomal membrane proteins belonging to the ATP binding cassette transporter superfamily.
  • PMID:22493507
    very long chain acyl-CoA esters are hydrolyzed by the Pxa1p-Pxa2p complex prior to the actual transport of their fatty acid moiety into the peroxisomes
  • PMID:8876235
    These genetic and physical data suggest that Pxa1p and Pxa2p heterodimerize to form a complete peroxisomal ABC transporter involved in fatty acid beta-oxidation.

References

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Suggested Questions for Experts

Q: Is the acyl-CoA thioesterase step intrinsic to the Pxa1p-Pxa2p transporter (as in PMID:22493507), and should GO describe the activity as fatty-acyl-CoA transport (GO:0015607) or as fatty acid transport coupled to acyl-CoA hydrolysis?

Suggested Experiments

Experiment: Reconstitute purified Pxa1p-Pxa2p in proteoliposomes with labelled acyl-CoA (CoA and acyl moieties separately labelled) to determine which moiety is translocated and whether ATP hydrolysis is coupled to thioester cleavage.

Deep Research

SGD

(PXA2-deep-research-sgd.md)
SGD gene description for PXA2 (yeast) SGD

SGD gene description for PXA2 (yeast)

Subunit of heterodimeric peroxisomal ABC transport complex, with Pxa1p; required for import of long-chain fatty acids into peroxisomes; similar to human adrenoleukodystrophy transportesr ABCD1 and ABCD2, and ALD-related proteins; mutations in ABCD1 cause X-linked adrenoleukodystrophy (X-ALD), a peroxisomal disorder; human ABCD1 and ABCD2 can each partially complement yeast pxa1 pxa2 double null mutant

πŸ“š Additional Documentation

Notes

(PXA2-notes.md)

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