Component of the Dot/Icm type IVB secretion system (T4BSS), which is used to inject bacterial effector proteins into eukaryotic host cells (PubMed:32513920). Part of a subcomplex which recruits effector proteins and delivers them to the core transmembrane subcomplex (PubMed:32513920). DotY and DotZ play a role in effector translocation, but are not essential and do not influence the stability of the subcomplex main components (PubMed:34816517). The DotY/DotZ main function is to optimize secretion by modulating the delivery trajectory of the IcmSW module and the localization of the machinery to the poles (PubMed:34816517). The T4BSS is a complex nanomachine composed of several subcomplexes. This subunit is part of the Type IV Coupling Complex (T4CC), a subcomplex composed of the DotLMNYZ core and the IcmSW-LvgA adapter subunits, linked by the C-terminal tail of DotL (PubMed:32513920). Six DotLMNYZ hetero-pentameric units may assemble into an hexameric nanomachine, forming an inner membrane channel for effectors to pass through (PubMed:32513920). Makes significant contact with DotN and DotY, but engages weakly with DotM and DotL (PubMed:32513920, PubMed:34816517). DotY and DotZ are co-dependent for the assembly into the T4CC (PubMed:34816517). Localizes to the poles of the cell. Localization depends on the fully assembled T4CC subcomplex. Deletion of the gene leads to a reduced intracellular growth in the protozoa A.castellanii and decreased levels of effector translocation (PubMed:32513920). Deletion of dotZ results in the absence of both DotY and DotZ proteins in the coupling complex (PubMed:34816517). Deletion mutant shows significantly reduced DotL polar localization (PubMed:34816517).