This family consists of several RIB43A-like eukaryotic proteins. Ciliary and flagellar microtubules contain a specialised set of protofilaments, termed ribbons, that are composed of tubulin and several associated proteins. RIB43A was first characterised in the unicellular biflagellate, Chlamydomonas reinhardtii although highly related sequences are present in several higher eukaryotes including humans. The function of this protein is unknown although the structure of RIB43A and its association with the specialised protofilament ribbons and with basal bodies is relevant to the proposed role of ribbons in forming and stabilising doublet and triplet microtubules and in organising their three-dimensional structure. Human RIB43A homologues could represent a structural requirement in centriole replication in dividing cells [1].

1: The Rib43a protein is associated with forming the specialized protofilament ribbons of flagellar microtubules in Chlamydomonas. Norrander JM, deCathelineau AM, Brown JA, Porter ME, Linck RW; Mol Biol Cell 2000;11:201-215. PMID:10637302