SCALE-DEPENDENT ELASTIC RESPONSE OF CLOSED PHOSPHOLIPID-BILAYERS TO TRANSMEMBRANE MOLECULAR PUMPING ACTIVITY - A KEY FOR EXO-ENDOCYTOSIS PHYSIOLOGICAL PROCESS

The question is asked on the physiological role of the universal molecular biological function activity of lipid transmembrane translocation in living-cell membranes. The elastic response of closed bilayers to phospholipid translocation is theoretically found to be scale dependent, leading to vesiculation for plasma membrane characteristic-size bilayers (R(m) approximate to 10 mu m), and to dilation strain for endocytic-vesicles characteristic-size bilayers (R(m) approximate to 0.1 mu m). Both vesiculation and dilation effects are experimentally proved. On the basis of this scaledependent behaviour, it is argued that transmembrane pumping activity could control both the vesiculation and the fusion process in vivo, namely the exo-endocytic cellular-membrane traffic process itself.