After repeated severe pneumonia, often

accompanied by otitis media, the young paediatrician can no longer think of

many options for further examinations of the young 5-year-old patient. After a

thorough immunoassay, which reveals no deficiency in cellular or antibody

immunity, the tissue sample is sent for further electron microscopic

examination. This examination demonstrates the rare Kartagener syndrome, which

leads to dysfunctional cilia. The cilia are present, but due to the lack of a

molecular motor, they are immobile and cannot perform their cleansing role,

which leads, among other things, to frequent infections with a more severe

course. What is the name of the molecular motor present between the

microtubules in the cilia?