PXA1 notes

Module: peroxisomal_beta_oxidation (substrate entry, abcd_transport_activity). PXA1/PXA2 are missing from YeastCyc YEAST-FAO-PWY.

Evidence journal

• Long-chain activated FA import via Pat1p/Pat2p (PXA2/PXA1) PMID:8670886.
• Heterodimer, coIP; not required for peroxisome assembly; Pxa1p unstable without Pxa2p [PMID:8876235 "Finally, we find that Pxa1p and Pxa2p coimmuno-precipitate."; "is associated with peroxisomes but not required for their assembly."].
• C18:1-CoA (not C8:0-CoA) import via Pxa2p, ATP-dependent PMID:9395310.
• Spectrum of acyl-CoAs; human ABCD1 complements PMID:18757502; ABCD2 also complements PMID:21145416.
• Mechanism: acyl-CoA hydrolysed by the complex, FA moiety translocated, re-esterified by Faa2p/Fat1p PMID:22493507.
• Pxa2p C-terminus required for Pxa1p interaction and function PMID:25118695.
• Also mediates unidirectional ATP uptake into peroxisomes PMID:35127709.

Curation decisions

• Core MF GO:0005324 long-chain fatty acid transmembrane transporter activity (fits the hydrolysis-then-FA-translocation mechanism; GOA IBA/IGI), BP GO:0015910, CC GO:0005778, complex GO:0043190.
• The module uses GO:0015607 ABC-type fatty-acyl-CoA transporter activity (acyl-CoA on both sides); this conflicts with PMID:22493507 and is not in GOA. Raised as a suggested question.
• IBA peroxisome organization: REMOVE (contradicted by PMID:8876235).
• MYTH protein-binding hits (PMID:23831759): REMOVE; Pxa1-Pxa2 coIP protein binding -> MODIFY to GO:0046982.
• ATP transport (IDA) and fatty-acyl-CoA transport (IGI): non-core.