Here, we wanted to compare the spatial structure of BoHV-1 UL49.to the non-TAP inhibitor HSV-1 UL49.5. Therefore, the aim of our research was to determine the structure of the HSV-1-encoded UL49.5 protein using an advanced model of ER membrane. We sought an answer to the question of what structural elements of the UL49.5 protein may be responsible for preventing antigen transport through the TAP protein channel based on the structural differences between the two proteins. The obtained results enable us to identify key structural components that distinguish HSV-1-encoded UL49.5 from its homolog and may be responsible for its biological properties, such as its inability to bind TAP.