An ATP13A1-assisted topogenesis pathway for folding multi-spanning membrane proteins

Published: 29 April 2024| Version 1 | DOI: 10.17632/j5x5pghh8m.1
, Meng-Ke Cui, Rong Zou, Ming-Zhi Wu, Man-Xi Ge, Jiqiang Li, Zai-Rong Zhang


Many multi-spanning membrane proteins contain poorly hydrophobic transmembrane domains (pTMDs) protected from phospholipid in mature structure. Nascent pTMDs are difficult for translocon to recognize and insert. How pTMDs are discerned and packed into mature, muti-spanning configuration remains unclear. Here, we report that pTMD elicits a post-translational topogenesis pathway for its recognition and integration. Using six-spanning membrane protein ABC transporter G2 (ABCG2) and cultured human cells as models, we show that its pTMD2 can pass through translocon into the ER lumen, yielding an intermediate with inserted yet mis-oriented downstream TMDs. After translation, the intermediate recruits P5A-ATPase ATP13A1, which facilitates TMD re-orientation, allowing further folding and the integration of the remaining lumen-exposed pTMD2. Depleting ATP13A1 or disrupting pTMD-characteristic residues arrests intermediates with mis-oriented and exposed TMDs. Our results explain how a “difficult” pTMD is co-translationally skipped for insertion and post-translationally buried into final correct structure at the late stage of folding to avoid excessive lipid-exposure.



Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Interdisciplinary Research Center on Biology and Chemistry


Biochemistry, Cell Biology