Figure 8.

Three possible models of LACS4 activation of IBA, which affects IBA metabolism to IAA in the peroxisome. (1) LACS4 and LACS6 are both located inside the peroxisome where together they charge IBA with CoA. LACS4 may localize solely to the peroxisome or also localize to the ER and/or cytoplasm. (2) LACS4 may exist in the cytoplasm and loosely associated with the peroxisome without being internalized by the organelle to generate a cytoplasmic pool of IBA-CoA. IBA-CoA is imported into the peroxisome where LACS6 can reattach the CoA onto IBA. (3) ER-localized LACS4 may generate a pool of IBA-CoA that is actively imported into the peroxisome or is contained within pre-peroxisome structures that become mature peroxisomes. CoA cleaved off during import is reattached by the peroxisomally contained LACS6.