PEX11s

PEX11s, or PEX11 family proteins, are small integral membrane proteins of peroxisomes that regulate peroxisome proliferation. They are encoded by PEX11 genes across eukaryotes and act at the stage of membrane remodeling to generate and elongate peroxisomal membranes, coordinating subsequent division. In mammals, the family includes PEX11alpha and PEX11beta, which have overlapping roles in maintaining peroxisome numbers in tissues such as liver and brain. In yeast and other fungi, multiple paralogs exist, including Pex11p, Pex25p, Pex27p, and Pex34p, each contributing to peroxisome dynamics and inheritance. Plants also possess PEX11 family members that participate in peroxisome division and distribution during development and in response to environmental cues.

Most PEX11 proteins are predicted to span the peroxisomal membrane two to three times, with both termini facing the cytosol. The N-terminal amphipathic helices and the ability to form oligomers promote membrane curvature and tubulation, creating elongations that are readily constricted by the dynamic fission machinery. In many organisms, PEX11 proteins recruit or cooperate with dynamin-related proteins such as DLP1/DRP1 (yeast Dnm1) and its receptors FIS1 and MFF to execute peroxisome fission. The abundance and activity of PEX11 on peroxisomes are influenced by metabolic state, including fatty acid availability, and changes in PEX11 levels correlate with peroxisome number and size.

Genetic disruption of PEX11 genes often impairs peroxisome proliferation, producing fewer, enlarged, or morphologically abnormal peroxisomes and altered peroxisomal metabolism. The PEX11 family is thus a conserved and essential component of the peroxisome division machinery in diverse eukaryotes.