9.B.198.2.6
GRAMD1A or Aster-A of 724 aas and 1 TMS near the C-terminus of the protein. It is a cholesterol transporter that mediates non-vesicular transport of cholesterol from the plasma membrane (PM) to the endoplasmic reticulum (ER) and  contains unique domains for binding cholesterol and the PM, thereby serving as a molecular bridge for the transfer of cholesterol from the PM to the ER. It plays a crucial role in cholesterol homeostasis and has the unique ability to localize to the PM based on the level of membrane cholesterol. In lipid-poor conditions, it localizes to the ER membrane, and in response to excess cholesterol in the PM is recruited to the endoplasmic reticulum-plasma membrane contact sites (EPCS) which is mediated by the GRAM domain. At the EPCS, the sterol-binding VASt/ASTER domain binds to the cholesterol in the PM and facilitates its transfer from the PM to ER. It may play a role in tumor progression, and plays a role in autophagy regulation while being required for biogenesis of the autophagosome which requires its cholesterol-transfer activity (Laraia et al. 2019).