The radial spokes and central apparatus: Mechano-chemical transducers that regulate flagellar motility

The radial spokes and central apparatus: mechano-chemical transducers that regulate flagellar motility.

Sequential assembly of flagellar radial spokes.

The unicellular alga Chlamydomonas can assemble two 10 μm flagella in 1 h from proteins synthesized in the cell body. Targeting and transporting these proteins to the flagella are simplified by preassembly of macromolecular complexes in the cell body. Radial spokes are flagellar complexes that are partially assembled in the cell body before entering the flagella. On the axoneme, radial spokes a...

FLAGELLAR MUTANTS LACKING RADIAL SPOKES AND CENTRAL TUBULES Structure, Composition, and Function of Specific Axonemal Components

The fine structure, protein composition, and roles in flagellar movement of specific axonemal components were studied in wild-type Chlamydomonas and paralyzed mutants pf-14, pf-15A, and p f-19. Electron microscope examination of the isolated axoneme of pf-14 showed that it lacks the radial spokes but is otherwise structurally normal. Comparison of isolated axonemes of wild type and pf-14 by sod...

Mechanosignaling between central apparatus and radial spokes controls axonemal dynein activity

Cilia/flagella are conserved organelles that generate fluid flow in eukaryotes. The bending motion of flagella requires concerted activity of dynein motors. Although it has been reported that the central pair apparatus (CP) and radial spokes (RSs) are important for flagellar motility, the molecular mechanism underlying CP- and RS-mediated dynein regulation has not been identified. In this paper...

Flagellar radial spokes contain a Ca2+-stimulated nucleoside diphosphate kinase.

The radial spokes are required for Ca(2+)-initiated intraflagellar signaling, resulting in modulation of inner and outer arm dynein activity. However, the mechanochemical properties of this signaling pathway remain unknown. Here, we describe a novel nucleoside diphosphate kinase (NDK) from the Chlamydomonas flagellum. This protein (termed p61 or RSP23) consists of an N-terminal catalytic NDK do...