Cholesterol depletion modulates detergent resistant fraction of human serotonin1A receptors

Abstract

Insolubility of membrane components in non-ionic detergents such as Triton X-100 at low temperature is a widely used biochemical criterion to identify, isolate and characterize membrane domains. In this work, we monitored the detergent insolubility of the serotonin_1A receptor in CHO cell membranes and its modulation by membrane cholesterol. The serotonin_1A receptor is an important member of the G-protein coupled receptor family. It is implicated in the generation and modulation of various cognitive, behavioral and developmental functions and serves as a drug target. Our results show that a significant fraction (～ 28%) of the serotonin_1A receptor resides in detergent-resistant membranes (DRMs). Interestingly, the fraction of the serotonin_1A receptor in DRMs exhibits a reduction upon membrane cholesterol depletion. In addition, we show that contents of DRM markers such as flotillin-1, caveolin-1 and GM₁ are altered in DRMs upon cholesterol depletion. These results assume significance since the function of the serotonin_1A receptor has previously been shown to be affected by membrane lipids, specifically cholesterol. Our results are relevant in the context of membrane organization of the serotonin_1A receptor in particular, and G-protein coupled receptors in general.