Membrane organization of the serotonin 1A receptor monitored by a detergent-free approach.

: 1. Insolubility of membrane constituents in nonionic detergents such as Triton X-100 has been a widely used biochemical criterion to indicate their localization in membrane domains. However, concerns on the possibility of membrane perturbation in the presence of detergents have led to the development of detergent-free approaches.2. We have explored the organization of the serotonin(1A) receptor, an important G-protein coupled receptor, from bovine hippocampus and CHO cells using a detergent-free approach in order to address the points of agreement with our previous results using Triton X-100.3. A significant fraction of the serotonin(1A) receptor has been found to be localized in a heavy density fraction obtained using a detergent-free approach to isolate membrane domains. In addition, we have characterized the membrane fractions isolated in terms of their lipid composition and membrane physical properties.4. The results obtained on the membrane localization of the serotonin(1A) receptor from the present experiments using a detergent-free approach correlate well with our earlier findings obtained using a detergent-based method (Kalipatnapu, S., and Chattopadhyay, A., FEBS Lett. 576:455-460, 2004). These results provide important information on the membrane organization of the hippocampal serotonin(1A) receptor and are relevant in view of the concerns on the use of detergent in determination of membrane organization of constituent proteins and lipids.