Required for endosome formation, vacuolar protein sorting and determination of the embryo growth axis. Necessary for the transport of proteins into protein storage vacuoles (PSVs). Participates in vesicle trafficking from the endosome to the central vacuole. Involved in the regulation of shoot phototropism and gravitropism, probably through the positioning of specialized amyloplasts (statoliths) in endodermal cells. Constitutively expressed in roots, hypocotyls, leaves (e.g. vascular tissues), stems, flowers (e.g. petals and stigmas), siliques and pollen. Expressed at the early to middle stages of seed maturation. Reduced shoot phototropism and gravitropism, and impaired embryo growth axis (e.g. between the late torpedo-shaped embryo stage and the walking stick-shaped embryo stage). Abnormal amyloplasts position and sedimentation in endodermal cells. Defect in the organization of endomembranes characterized by aggregated endomembrane structures accompanied by a missorting of storage proteins. 'Katamari' means 'aggregate' in Japanese.