Membrane localization triggers strong complex formation for pairs of protein binding partners involved in clathrin-mediated endocytosis.

<p>(a) Interactions between lipid binding human (green) and yeast (blue) CME proteins are shown along with K_d^PP values (μM) measured (red text), inferred through structural and functional homology (green), or estimated (blue) (<a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1006031#pcbi.1006031.t001" target="_blank">Table 1</a>, <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1006031#pcbi.1006031.s003" target="_blank">S1 Table</a>, <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1006031#pcbi.1006031.s009" target="_blank">S3 Dataset</a>). Sizes indicate concentrations (<a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1006031#pcbi.1006031.t001" target="_blank">Table 1</a>). (b) Enhancements for each of these CME binding pairs, following the model of <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1006031#pcbi.1006031.g001" target="_blank">Fig 1</a>, were calculated using <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1006031#pcbi.1006031.e006" target="_blank">Eq 3</a> and verified through numerical simulation of ODEs. Pairs involving human AP-2 are in dark green, light green points involve AP-2 with cargo binding-adjusted K_a^PM, with red and blue points showing other human and yeast proteins, respectively. The x-axis is the average membrane stickiness for each pair, and here we assume σ = 1nm (see <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1006031#pcbi.1006031.s015" target="_blank">S5 Fig</a> for σ = 10nm). For poorly characterized lipid binding affinities, we considered ranges of values (error bars in x), producing ranges of enhancements (error bars in y). Gray lines are guides for fixed V/A ratios. Protein names in parentheses are homo-dimers. (c) The percent of proteins in complexes increases from solution binding levels (gray bars) as a result of membrane localization (colored bars). All results and parameters used for all data points in <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1006031#pcbi.1006031.s009" target="_blank">S3 Dataset</a>.