Restoration of the Excitability of Squid Giant Axon by Tubulin—Tyrosine Ligase and Microtubule Proteins1

Membrane excitability of the squid giant axon was destroyed by perfusing with a medium containing 0.2 mM Ca ions that depolymerize microtubules. Restoration of the membrane excitability was achieved by perfusing the axon with a medium that contained purified tubulin-tyrosine ligase, tubulin, ATP, Mg2+, K+, cyclic AMP, and 300 K Protein.