Tektin interactions and a model for molecular functions.
Tektins from echinoderm flagella were analyzed for microheterogeneity, self-associations and association with tubulin, resulting in a general model of tektin filament structure and function applicable to most eukaryotic cilia and flagella. Using a new antibody to tektin consensus peptide RPNVELCRD, well-characterized chain-specific antibodies and quantitative gel densitometry, tektins A, B and C were found to be present in equimolar amounts in Sarkosyl-urea-stable filaments. In addition, two isoforms of tektin A are present in half-molar ratios to tektins B and C. Cross-linking of AB filaments indicates in situ nearest neighbor associations of tektin A1B and A2B heterodimers, -trimers, -tetramers and higher oligomers. Soluble purified tektin C is cross-linked as homodimers, trimers and tetramers, but not higher oligomers. Tektin filaments associate with both loosely bound and tightly bound tubulin, and with the latter in a 1:1 molar ratio, implying a specific, periodic association of tightly bound tubulin along the tektin axis. Similarly, in tektin-containing Sarkosyl-stable protofilament ribbons, two polypeptides ( approximately 67/73 kDa, homologues of rib72, efhc1 and efhc2) are present in equimolar ratios to each other and to individual tektins, co-fractionating with loosely bound tubulin. These results suggest a super-coiled arrangement of tektin filaments, the organization of which has important implications for the evolution, assembly and functions of cilia and flagella.
Setter
Peter W
PW
Department of Genetics, Cell Biology and Development, University of Minnesota, 321 Church St., Minneapolis, MN 55455, USA.
Malvey-Dorn
Erika
E
Steffen
Walter
W
Stephens
Raymond E
RE
Linck
Richard W
RW
D000818:Animals; D002923:Cilia / Q000378:metabolism; D019143:Evolution, Molecular; D008297:Male; D008868:Microtubule Proteins / Q000737:chemistry* / Q000378:metabolism*; D008870:Microtubules / Q000648:ultrastructure; D008954:Models, Biological; D011108:Polymers / Q000378:metabolism; D012521:Sarcosine / Q000031:analogs & derivatives / Q000378:metabolism; D012617:Sea Urchins / Q000166:cytology / Q000378:metabolism; D013082:Sperm Tail / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D014404:Tubulin / Q000378:metabolism; D014508:Urea / Q000378:metabolism
D008868:Microtubule Proteins; D011108:Polymers; D014404:Tubulin; C044103:tektins; C025231:sarkosyl; D014508:Urea; D012521:Sarcosine