A component of FAZ filament that is required for correct FAZ assembly and attachment. Not essential for new flagellum growth. The flagellum attachment zone (FAZ) is a complex structure comprising a FAZ filament structure, a specialised microtubule quartet (MtQ) and the plasma membrane attachment, a specialised area of flagellum. Assembly of a compromised FAZ and defects in flagellum attachment and cytokinesis in procyclic trypanosomes resulting in generation of 0N1K cells (zoids) and multinucleated cells, demonstrates the role of an attached flagellum in cellular morphogenesis.