KINESIN-RELATED PROTEINS IN EUKARYOTIC FLAGELLA

To identify kinesin-related proteins that are important for ciliary an d eukaryotic flagellar functions, we used affinity-purified, polyclona l antibodies to synthetic peptides corresponding to conserved sequence s in the motor domain of kinesin (Sawin et al. (1992) J. Cell Sci. 101 , 303-313). Using immunoblot analysis, two antibodies to distinct sequ ences (LNLVDLAGSE, 'LAGSE' and, HIPYRESKLT, 'HIPYR') reveal a family o f proteins in flagella and axonemes isolated from Chlamydomonas. Simil ar analysis of axonemes from mutant Chlamydomonas strains or fractiona ted axonemes indicates that none of the immunoreactive proteins are as sociated with dynein arm or spoke structures. In contrast, one protein , similar to 110 kDa, is reduced in axonemes from mutant strains defec tive in the central pair apparatus. Immunoreactive proteins with masse s 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 mic rotubules 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 re sponses in Chlamydomonas.