Transmembrane Protein 109 (TMEM109)

Mitsugumin 23 (MG23) is a 23 kDa transmembrane protein localized to the sarcoplasmic/endoplasmic reticulum and nuclear membranes in a wide variety of cells. Hydropathicity profile and limited proteolytic analysis proposed three transmembrane segments in the MG23 primary structure. Chemical cross-linking analysis suggested a homo-oligomeric assembly of MG23. Ultrastructural observations detected a large symmetrical particle as the predominant component and a small asymmetric assembly as the second major component in highly purified MG23 preparations. MG23 forms a large bowl-shaped complex equipped with a putative central pore, which is considered an assembly of the small asymmetric subunit. the bowl-shaped MG23 can transiently assemble and disassemble.