8.A.97.1.1
The vacuolar membrane protein 1, VMP1 scramblase (also called TDC1, TMEM49 and HSPC 292) of 406 aas and 8 - 10 TMSs (possibly in a 3 + 1 + 3 + 1 TMS arrangement). It is a regulator of the SERCA Ca²⁺-ATPase (Zhao et al. 2017). However, the release of lipoproteins from the ER membrane requires VMP1, an ER transmembrane protein essential for autophagy and certain types of secretion (Morishita et al. 2019). Loss of Vmp1, but not other autophagy-related proteins, in zebrafish causes lipoprotein accumulation in the intestine and liver. Vmp1 deficiency in mice also leads to lipid accumulation in the visceral endoderm and intestine. In VMP1-depleted cells, neutral lipids accumulate within lipid bilayers of the ER membrane, thus affecting lipoprotein secretion. Thus, VMP1 may mediate the release of lipoproteins from the ER membrane to the ER lumen (Morishita et al. 2019). TMEM41B and VMP1, two endoplasmic reticulum (ER)-resident transmembrane proteins, play important roles in regulating the formation of lipid droplets (LDs), autophagy initiation, and viral infection. TMEM41B and VMP1 are critical to the normal distribution of cholesterol and phosphatidylserine. Both proteins have scramblase activity, thus shedding light on the mechanism by which TMEM41B and VMP1 regulate LD formation, lipid distribution, macroautophagy, and viral infection (Zhang et al. 2021). The effect of VMP1 on the treatment of pressure overload-induced pathological cardiac hypertrophy involving SERCA-regulated autophagic flux (Liu et al. 2023).