Spontaneously assembled CXCR4 dimers.

<p>(<b>a</b>) Sampled CXCR4 dimer configurations in pure POPC bilayers after 3 <i>μ</i>s (left), and in mixed POPC:cholesterol bilayers after 6 <i>μ</i>s simulation time at 10% (middle) and 30% cholesterol content (right). The <i>β</i> and <i>χ</i> angles are defined relative to the crystal TM5,6/TM5,6 interface (central blue dots, see <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1005169#sec008" target="_blank">Methods</a> Section for the exact definition of the angles <i>β</i> and <i>χ</i>). (<b>b</b>) Relative populations for the dimer configurations defined in (a) and (c). (<b>c</b>) Representative dimer configurations corresponding to labeled maxima <i>A</i> to <i>G</i> in (a) are shown in cylindric representation and colored equally as in <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1005169#pcbi.1005169.g001" target="_blank">Fig 1</a>. Symmetric structures (<i>C1</i> and <i>C2</i> corresponding to TM1/TM5 and TM5/TM1, respectively) are distinguished by indices 1 and 2. The reference structure for all dimer configurations is indicated by green and blue axes.