An update on axon initial segment structure and function

Abstract

The axon initial segment (AIS) is a specialized subcellular region located at the proximal end of the axon and serves as the action potential initiation site due to the high density of ion channels. The AIS plays a critical role in maintaining neuronal polarity by regulating the trafficking and distribution of proteins that function in the dendritic or axonal compartment of the neuron. Due to the adaptive nature of AIS location and length, the excitability of neurons can be altered in response to activity. In this review, we briefly introduce the structure and function of AIS as well as discuss the recent progress in our understanding of AIS ion channel distribution and plasticity in different types of neurons. These would contribute to a better understanding of the AIS and give us a new perspective on AIS-related diseases.