The putative reentrant loop domain of ANO1 facilitates channel activation

Abstract

The calcium-activated chloride channel ANO1 (TMEM16A) regulates multiple physiological processes, including fluid secretion, smooth muscle constriction and neuronal excitability. However, little is known about the processes leading to activation of the channel. Here we report the results of an unbiased approach to investigate the structure-function relationship of ANO1. By using high-throughput, random mutagenesis we generated and functionally characterized a library of ~6000 mutants of ANO1. Our data indicate a critical role of residues AA 736-742 in the regulation of the calcium sensitivity and activation of ANO1. Our newly identified Furthermore, we report mutations affecting the intracellular trafficking and localization of ANO1. Our data provides novel insight in the functional composition of the quaternary structure of ANO1 and is consistent with ANO1 forming a dimer with two independent pores. In summary, our data provides the first, unbiased and comprehensive study of the structure-function relationship of ANO1. Our newly identified mutants of ANO1 exhibiting diverse functional characteristic provide a new tool to study ANO1 function in biological systems and pave the path for a better understanding of the function of anoctamins and their role in diseases