Substructure of inner dynein arms, radial spokes, and the central pair/projection complex of cilia and flagella.
The substructure of the components of the axoneme interior--the inner dynein arms, the radial spokes, and the central pair/projection complex--was analyzed for Chlamydomonas. Tetrahymena, Strongelocentrotus, and Mnemiopsis using the quick-freeze, deep-etch technique. The inner arms are shown to resemble the outer arms in overall molecular organization, but they are disposed differently on the microtubule and have two distinct morphologies--dyads with two heads and triads with three. The dyads associate with spokes S3 and S2; the triads associate with S1. The spokes form a three-start right-handed helix with a 288-nm rise; the central pair makes a shallow left-handed twist. The spoke heads are shown to be made up of four major subunits; two bind to the spoke shaft and two bind to a pair of central-sheath projections.
Goodenough
U W
UW
Heuser
J E
JE
D000818:Animals; D002696:Chlamydomonas / Q000648:ultrastructure; D002923:Cilia / Q000648:ultrastructure*; D003063:Cnidaria; D005407:Flagella / Q000648:ultrastructure*; D005613:Freeze Etching; D008854:Microscopy, Electron; D008870:Microtubules / Q000648:ultrastructure; D012617:Sea Urchins / Q000648:ultrastructure; D013768:Tetrahymena / Q000648:ultrastructure