Title: Multiple Roles of Macromolecules in Excitable Cells:
Consideration of a 'Minimal Excitable Unit.'
Abstract: Fibrillar macromolecular networks are ubiquitous in
biological systems, from cellular cytoskeletons to tissues such as muscle
and tendon. The presence of such networks in neuronal tissue is known -
for example in the cytoskeleton and extracellular matrix in and around
neuronal and glial cells - but their function is believed to be
principally mechanical/structural in nature. However, there has long been
speculation regarding a broader role for neuronal fibrillar
macromolecules, which are anionic polyelectrolytes, specifically regarding
their participation in nervous stimulation and transmission. This area
will be reviewed and will culminate in a proposal of a 'minimal excitable
unit,' which is effectively a composite system which comprises a lipid
bilayer and associated membrane proteins with a fibrillar polyelectrolyte
network underneath. Physiological implications will be discussed.