Side view of our conceptualization of the receptor-mediated internalization process.

<p>The dash-dotted line is the axis of rotational symmetry. Ligand density (<i>ξ</i>_l) and receptor density (<i>ξ</i>_r) are assumed comparable. Bond density (<i>ξ</i>_b) is a function of the curvilinear coordinate, <i>s</i>, and of time, <i>t</i>. The elevation of the particle center above the initial cell membrane position is denoted by <i>Z</i>₀(<i>t</i>). The membrane position is defined by its coordinates <i>R</i>(<i>s</i>, <i>t</i>) and <i>Z</i>(<i>s</i>, <i>t</i>).