Membrane changes in a circadian system

Abstract

NJUS et al.¹ have recently suggested a membrane model of a biological clock and propose that the clock mechanism is a feedback oscillator in which the ion transport channels envisaged in the fluid mosaic model of cellular membranes² are involved directly. It is postulated that the proteins which make up these channels respond to changes in concentration gradients of specific ions in the membrane, by grouping to form transport channels when the gradient is small, and dispersing to non-transporting modes when the gradient is large. Thus the protein distribution in the membrane could be regulated by the oscillating ionic gradient and could itself regulate the ionic gradient to complete the feedback pathway and drive the oscillation. It has also been suggested^3–5 that oscillatory changes at cellular membranes may be directly associated with the clock mechanism, based on observations that the phase or the period of the oscillation can be changed by treatments which affect the passage of ions through membranes.