Here we report a study of molecular dynamics of a YCD2 fragment of mammalian tyrosyl-tRNA synthethase (Asp322-Ser528), which includes the COOH-terminal cytokine-like domain, intermodular flexible linker, and H5-a-helix of catalytic core of synthetase. Our calculations show that while compact C-terminal domain was less flexible and relatively stable, the interdomain linker shows a high degree of conformational changes. After short relaxation time it forms a short helix-like structure, which may be involved in the regulation of domain interaction and modulation of protein activities.