ARV1 transports CHOL from ER membrane to plasma membrane

Sterols such as cholesterol (CHOL) synthesised in the endoplasmic reticulum (ER) need to be efficiently transported to the plasma membrane, where 90% of the free sterol pool resides. Conversely, sterols taken up from outside the cell need to be transported back to the ER for esterification to sterol esters. The mechanisms that control this bi-directional movement of sterols are still poorly understood but a likely candidate is protein ARV1 (ARV1). Studies with mutant yeast Arv1 indicate altered intracellular sterol distribution and subsequent defects in sphingolipid metabolism. Human ARV1, a predicted sequence ortholog of yeast Arv1, complements the defects seen associated with deletion of yeast Arv1 (Tinkelenberg et al. 2000, Swain et al. 2002).

类固醇如胆固醇（CHOL），在粗面内质网（ER）中合成，需高效运输至质膜，其中游离类固醇库的90%驻留于此。反之，从细胞外摄取的类固醇需运输回ER进行酯化生成类固醇酯。调控此类固醇双向运输的机制尚不明确，但蛋白质ARV1（ARV1）可能为潜在候选者。对突变酵母Arv1的研究表明，其细胞内类固醇分布发生改变，进而导致鞘脂代谢缺陷。人类ARV1，作为酵母Arv1预测序列的直系同源物，可补充酵母Arv1缺失所见的缺陷（Tinkelenberg等，2000年，Swain等，2002年）。