THE SECRETORY EPITHELIAL-CELLS OF THE CHOROID-PLEXUS EMPLOY A NOVEL KINESIN-RELATED PROTEIN

The proteins of the kinesin superfamily (KIFs) are microtubule-based m olecular motors whose functions include the transport of membrane-boun d organelles. We have isolated the cDNA encoding a novel kinesin by re verse transcription and polymerase chain reaction using degenerate pri mers that flank the highly conserved motor domain. The deduced amino a cid sequence of this protein shows considerable similarity to both KIF 1A and KIF1B thus defining it as a new member of the monomeric KIF1/un c104 family. The C-terminal domain of KIF1D is the most divergent by c omparison with the other members of the family, which supports the vie w that the tail region is responsible for conferring specificity on th e interactions of these kinesins with their cargoes. In the adult rat brain KIF1D mRNA is expressed in neurons in the hippocampus and in the Purkinje cells of the cerebellum. However, the levels of KIF1D are pa rticularly high in the choroid plexus which is a polarised epithelium that lines the lateral, third and fourth ventricles. The major functio n of the epithelial cells in the choroid plexus is to produce cerebros pinal fluid, which suggests that KIF1D plays an important role in thei r secretory function. (C) 1997 Elsevier Science B.V.