Protein complex that links the outer microtubule doublet of a 9+2 type ciliary or flagellar axoneme with the sheath that surrounds the central pair of microtubules. Composed of a stalk that attaches to each doublet microtubule and a globular structure (spoke head) that projects toward the central pair of microtubules. [ http://www.ncbi.nlm.nih.gov/pubmed/22118931 http://www.ncbi.nlm.nih.gov/pubmed/9450971 https://www.worldcat.org/search?q=bn%3A0124325653 GOC:krc http://www.ncbi.nlm.nih.gov/pubmed/25694453 http://www.ncbi.nlm.nih.gov/pubmed/34871179 ]
Term information
goslim_pir
Radial spokes are involved in some types of beating motions of the cilium. The radial spoke is usually a T-shaped structure comprised of a short base that attaches to the A-microtubule of an axonemal outer microtubule doublet (MTD) of a cilium, an elongated stalk, a neck complex, and an orthogonal head structure that extends perpendicularly towards the inner sheath and the central pair (CP) microtubules. Groups of radial spokes (RSs) repeat along the MTD with regular spacing. In most organisms, each group of radial spokes is comprised of a triplet of spokes: RS1, RS2, and RS3. In some organisms (e.g. Chlamydomonas and Sarcophaga bullata), each group contains a doublet of radial spokes: RS1 and RS2, while RS3 is represented only as a stump (referred to as RS3S) attached to the A-microtubule but lacking the rest of the stalk structure and entirely lacking the head structure.