GRAMD1A
Description
The GRAMD1A (GRAM domain containing 1A) is a protein-coding gene located on chromosome 19.
GRAMD1A, also known as Aster-A, is a cholesterol transporter that facilitates non-vesicular movement of cholesterol from the plasma membrane (PM) to the endoplasmic reticulum (ER). It contains distinct domains for binding cholesterol and the PM, acting as a molecular bridge for cholesterol transfer. GRAMD1A plays a critical role in cholesterol homeostasis and has the unique ability to localize to the PM based on membrane cholesterol levels. In lipid-poor conditions, it resides in the ER membrane, but in response to excess cholesterol in the PM, it is recruited to the endoplasmic reticulum-plasma membrane contact sites (EPCS) via its GRAM domain. At the EPCS, the sterol-binding VASt/ASTER domain binds to cholesterol in the PM and facilitates its transfer to the ER. GRAMD1A may also be involved in tumor progression. Importantly, it plays a role in autophagy regulation and is essential for autophagosome biogenesis, a process that depends on its cholesterol-transfer activity. (PubMed:31222192)
GRAMD1A is also known as KIAA1533.
