It has been observed that various domains in ARSs, though situated distantly, coordinate with each other for carrying out the enzymatic function with great precision. However, the molecular mechanism of this interdomain coordination in ARSs has remained poorly understood. How do these domains communicate with each other? Does protein dynamics play a role on these long-range communications? Do these communications propagate through space? To explore these questions we are currently studying the domain motions in two ARSs, the class I leucyl-tRNA synthetase and class II prolyl-tRNA synthetase. We are studying the domain motions and exploring if the communication among the various domains of an ARS can be accomplished through cooperativities of these domain motions.