Identification of the potential function-specific sites in subunits of vertebrate neuronal nicotinic acetylcholine receptors

The nicotinic acetylcholine receptors (nAChR) are complexes that are composed of subunits evolved from common ancestor. Although the subunits are similar in sequences and structures, their molecular function varies significantly. Therefore, detecting the molecular sites specific to each subunit is important to understand the property of the subunits and the receptors formed by them. As we know, the molecular sites critical to the structure and molecular function of a protein family usually are conserved in evolution, and those specific to each member of the family are often closely related to its structural and functional specificity. In this study, we analyzed the sequence specific sites in nAChR subunits by adopting the evolutionary trace method and the two-state model, and explored the relationship between structure and function in combination with the spatial location of the sites. The results showed that the detected sites in 7 subunit were closely related to ligand binding and conformational changes of the energetic coupling pathway. The conserved sites tended to be distributed in the interior of the spatial structure of protein molecules, and the sites potentially related to new functions were distributed on the surface of the spatial structure. In summary, our results could be helpful to understanding the molecular features related to the function specificity and diversity of the nAChR subunits.