| Essential roles of the NH 2 terminal extension of valyl tRNA synthetase and of the EF 1 delta subunit in complex formation . ^^^ The results demonstrate that the NH 2 terminal extension of valyl tRNA synthetase is required for complex formation and that the enzyme binding site ( s ) resides on the EF 1 delta subunit . ^^^ Moreover , although the EF 1 beta gamma binary complex does not bind valyl tRNA synthetase , it is nevertheless required for assembly of a complex of defined quaternary structure by preventing the formation of high molecular weight aggregates generated in the presence of EF 1 delta alone . . ^^^ |