Kinesin-related proteins in eukaryotic flagella.

To identify kinesin-related proteins that are important for ciliary and eukaryotic flagellar functions, we used affinity-purified, polyclonal antibodies to synthetic peptides corresponding to conserved sequences in the motor domain of kinesin (Sawin et al. (1992) J. Cell Sci. 101, 303-313). Using immunoblot analysis, two antibodies to distinct sequences (LNLVDLAGSE, 'LAGSE' and, HIPYRESKLT, 'HIPYR') reveal a family of proteins in flagella and axonemes isolated from Chlamydomonas. Similar analysis of axonemes from mutant Chlamydomonas strains or fractionated axonemes indicates that none of the immunoreactive proteins are associated with dynein arm or spoke structures. In contrast, one protein, approximately 110 kDa, is reduced in axonemes from mutant strains defective in the central pair apparatus. Immunoreactive proteins with masses of 96 and 97 kDa (the '97 kDa' proteins) are selectively solubilized from isolated axonemes in 10 mM ATP. The 97 kDa proteins co-sediment in sucrose gradients at about 9 S and bind to axonemes or purified microtubules in a nucleotide-dependent fashion characteristic of kinesin. These results reveal that flagella contain kinesin-related proteins, which may be involved in axonemal central pair function and flagellar motility, or directed transport involved in morphogenesis or mating responses in Chlamydomonas.