SF-assemblin, striated fibers, and segmented coiled coil proteins

The flagellar basal apparatus of many flagellate green algae contains noncontractile striated microtubule-associated fibers (SMAFs). The SMAFs consist of 2-nm protofilaments and are predominantly built from striated fiber (SF)-assemblin, an acidic 33-kDa protein. In this review we summarize the present knowledge concerning the biochemical properties of SF-assemblin and the molecular architecture of the SMAFs, provide evidence for homologous proteins and similar filament systems in other eukaryotes, and, finally, discuss possible biological functions of SF-assemblin.