InterPro domain: IPR001708

This entry includes membrane insertase YidC from bacteria, ALBINO3-like proteins from plants, and mitochondrial membrane insertase OXA1 and cytochrome c oxidase assembly protein COX18 from eukaryotes. They are a group of evolutionarily conserved proteins that function in membrane protein integration and protein complex stabilization. They share a conserved region composed of five transmembrane regions [ 1 ].

YidC is required for the insertion of integral membrane proteins into the membrane. It may also be involved in protein secretion processes [ 2 ].

COX18 is a mitochondrial membrane insertase required for the translocation of the C terminus of cytochrome c oxidase subunit II (MT-CO2/COX2) across the mitochondrial inner membrane. It plays a role in MT-CO2/COX2 maturation following the COX20-mediated stabilization of newly synthesized MT-CO2/COX2 protein and before the action of the metallochaperones SCO1/2 [ 3 ].

OXA1 is a mitochondrial inner membrane insertase that mediates the insertion of both mitochondrion-encoded precursors and nuclear-encoded proteins from the matrix into the inner membrane. It links mitoribosomes with the inner membrane [ 4 ].

Plant ALBINO3-like proteins are required for the insertion of some light harvesting chlorophyll-binding proteins (LHCP) into the chloroplast thylakoid membrane [ 5 , 6 ].

1. YidC/Alb3/Oxa1 Family of Insertases. J. Biol. Chem. , 14866-74
2. Structure of YidC from Thermotoga maritima and its implications for YidC-mediated membrane protein insertion. FASEB J. 290, fj201700893RR
3. Human mitochondrial cytochrome c oxidase assembly factor COX18 acts transiently as a membrane insertase within the subunit 2 maturation module. J. Biol. Chem. 292, 7774-7783
4. Oxa1-ribosome complexes coordinate the assembly of cytochrome C oxidase in mitochondria. J. Biol. Chem. 287, 34484-93
5. Genetic and Physical Interaction Studies Reveal Functional Similarities between ALBINO3 and ALBINO4 in Arabidopsis. Plant Physiol. 169, 1292-306
6. Alb4 of Arabidopsis promotes assembly and stabilization of a non chlorophyll-binding photosynthetic complex, the CF1CF0-ATP synthase. Mol Plant 2, 1410-24