Phase separation of the receptor for immunoglobulin E and its subunits in Triton X-114

Document Type

Journal Article

Publication Date



Journal of Biological Chemistry






Above its critical micelle concentration, Triton X-114 in solution forms two phases at room temperature: a lower phase containing supramicellar aggregates and an upper phase largely depleted of detergent. This property of the detergent is potentially useful for separating under mild conditions proteins that bind detergent from those that do not (Bordier, C. (1981) J. Biol. Chem. 256, 1604-1607). We studied the distribution of the receptor for immunoglobulin E (IgE) and its subunits in the two phases. IgE and IgE complexed either with intact receptors or with the γa chains of the receptor alone are principally partitioned into the upper phase, whereas the unliganded receptor as well as the isolated α, and especially the β and γ chains of the receptor, preferentially partition into the lower detergent phase. Chromatography of IgE and of the subunits of the receptor on a hydrophobic support showed that the β and γ chains have a considerably greater hydrophobic surface than the α chains or IgE. These results indicate that the distribution of a protein in the two phases of phase-separated Triton X-114 is not an all-or-none effect based upon whether it binds detergent or not. Rather, it reflects the overall balance between the hydrophobic and hydrophilic properties of the protein's surface.

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