Self-electrophoresis of membrane molecules and chromosomes: Unifying hypothesis of cell cycle controls

Abstract

A hypothesis is proposed that the decoding ability of the cell membrane to various factors promoting cell growth and division (hormones, growth factors, antigens, etc.) is based on movement and aggregation of the ligand-receptor complexes and other charged membrane subunits by self-electrophoresis in the plane of the membrane. This mechanism is proposed to be involved in two main membrane functions. It is responsible for activation and regulation of membrane-bound enzymes such as the adenylate-guanylate cyclase control system by directing the ligand-receptor complex to the distant acceptor structure (the separate cyclase molecule). Self-electrophoresis of charged subunits in the plane of the membrane causes furthermore changes in the local surface charge density of the membrane. This, through the effect on the local surface tension, which is the tractional force of the cell, causes either contraction or expansion of the cell membrane and produces the phenomena of pinocytosis and microvilli formation respectively. The self-electrophoresis hypothesis predicts that microvilli are electric entities which provide visual markers of the number and distribution of local electric fields of the cell. Elaboration of a great many randomly distributed microvilli during interphase causes depolarization of the cell which in turn has the following consequences in regard to the co-ordination of the cell cycle events. (1) The depolarized state, i.e. increased intracellular Na + content is a pre-requisite for DNA synthesis. (2) Depolarization causes unfolding of previously-accumulated microvilli. This process begins at the polar areas and is responsible for cytokinesis. (3) The unfolding of microvilli at the poles is accompanied by redistribution of the local electric fields of the cell: A great many randomly distributed fields (in interphase) are replaced by one equator-to-poles electric field (in mitosis). Since microtubules and microfilaments as well as their constituent subunits have a permanent electric dipole moment along the longitudinal axis, their reversible assembly-disassembly is controlled by these changes in distribution of local electric fields of the cell. The daughter chromosomes are separated by self-electrophoresis in the equator-to-poles electric field during anaphase.