Pf-ribbon

Cilia and flagella appear to be stable, terminal, microtubule-containing organelles, but they also elongate and shorten in response to a variety of signals. To understand mechanisms that regulate flagellar dynamics, Chlamydomonas cells with nongrowing flagella were labeled with (35)S, and flagella and basal body components were examined for labeled polypeptides. Maximal incorporation of label into the flagella occurred within 3 h. Twenty percent of the flagellar polypeptides were exchanged. These included tubulins, dyneins, and 80 other axonemal and membrane plus matrix polypeptides...

Biochemical fractionation of axonemal microtubules yields the protofilament ribbon (pf-ribbon), an insoluble structure of 3-4 longitudinal protofilaments composed primarily of alpha/beta tubulin, tektins A, B and C, and two previously uncharacterized polypeptides of 77 kDa and 83 kDa. We have isolated the 77/83 kDa polypeptides (termed Sp77 and Sp83) from sperm flagella of the sea urchin Stronglyocentrotus purpuratus and raised polyclonal antibodies against them. Sp77 and Sp83 copurify exclusively with the pf-ribbon...