The Modulation of Protein Phosphorylation and Receptor Binding in Synaptic Membranes by Changes in Lipid Fluidity: Implications for Ageing

Abstract

Publisher Summary Phosphorylation and dephosphorylation of membrane proteins are intermediate steps in signal transduction by hormones and neurotransmitters. These processes are regulated by cyclic nucleotides and by ions, and are probably dependent on membrane dynamics. Complex, sequential membranal events can be classified into two categories: active (metabolically driven) and passive. Active processes are characterized by energy consumption, (for example, ATP-linked) which can be blocked by metabolic poisons and low temperatures. These processes are long-term in nature and require a specific compartmental strucutre. Most of these processes are associated with the cytoskeletal network. Passive processes, on the other hand, are directly related to diffusion (lateral, rotational or vertical) and are largely determined by membrane lipid fluidity. These processes do not require metabolic energy and can proceed in isolated membranes. Therefore, alteration of membrane lipid fluidity can, passively and instantaneously, modulate receptors, antigens and enzymes. This chapter describes the passive modulation of protein phosphorylation and receptor binding by in vitro or in vivo lipid manipulations.