The mother centriole forms the basis of the primarycilium. As the cilium assembles, the mother centriolematures and differentiates into the basal body, and a numberof fibrous structures are formed that add to the complexity,including the distal and subdistal appendages. Anumber of the proteins corresponding to these structuresare identified already, but given the complexity of thebasal body, the macromolecular composition of some ofthese appendages remain unknown. To date, the proteinsninein and Cep170 are believed to be a part of the subdistalappendages, and Cep164, outer dense fiber 2, ODF2/cenexin, Cep290, Ofd1 compose the distal appendages.Most of these appendage structures have been reported toplay a role for cilia assembly. We previously characterizedthe centrosome proteome of human lymphoblastic KE-37cells using quantitative mass spectrometry, which identified40 novel candidate proteins (Jakobsen et al., 2011).Using immunoflourescence- and immunogold electronmicroscopy on different human culture cells we identifiedproteins localizing asymmetrically to the centrioles, andtwo of these appeared to be new appendage proteins, onedistal- (Cep37) and one subdistal (Cep128). Interestingly,in addition Cep37 also localize to the ciliary tip and morefaintly along the axoneme. Preliminary results indicatethat depletion of Cep37 reduces length of cilia in RPEcells. Cep128 does not affect RPE or hFF cells ability toform primary cilia, but they do show a higher number ofpericentriolar dense bodies or satellites as well as a highernumber of non exocytotic vesicles in line with the cilium.
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