Recoverin is an important branch of neuronal calcium sensor. To clarify the coupling/decoupling interaction mechanism between EF-hands and Ca2＋, a series of constant force pulling and constant velocity pulling non-equilibrium molecular dynamics simulations were performed by using a steered molecular dynamics method. The results show that, among the residues in the EF-2 and EF-3 loop motifs, the orders of chelation abilities are Asn-76＜Thr-80＜Glu-85＜Asp-74＜Asp-78 and Thr-116＜Glu-121＜Asp-110＜Asn-114＜Asp-112, respectively. The coupling interaction between EF-3 and Ca2+ is more powerful than that between EF-2 and Ca2＋. The residues of Asp-78 and Asp-112 in the EF-hand loops play vital roles in the conformational transition involving signal transduction. According to the theoretical simulation and experimental results, it is safe to make the conclusion that the Ca2＋-recoverin allostery is a two-step process. In the cell signal process of Ca2＋ coupling with recoverin, the interaction of Ca2＋ with EF-3 triggers the conformational transition of recoverin, whereas it is carried over by Ca2＋ interacting with EF-2, which makes the transition completely.

Key words: recoverin, conformational transition, signal transduction, decoupling interaction, steered molecular dynamics, Ca2＋/myristoyl switch