An iris-like pore for protein import into peroxisomes

A peroxisomal PEX13 channel forms an iris-like pore that dilates from ~52 Å to ~70 Å, enabling import of folded PEX5 receptor–small cargo.

• Why it matters: How folded, sometimes oligomeric proteins cross the peroxisomal membrane through the YG-rich phase is unclear, limiting understanding of size-dependent cargo translocation.
• What they did: Structures show twelve PEX13 molecules assemble into a ring of tilted amphipathic helices with YG-rich pore lining; helix sliding changes tilt and pore diameter.
• The result: The pore widens further to ~100 Å for the largest cargo, supported by AlphaFold modeling and disulfide crosslinking, suggesting an adaptive conduit for folded proteins of varying sizes.