Microtubule-membrane interactions in cilia. I. Isolation and characterization of ciliary membranes from Tetrahymena pyriformis.

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Abstract
Tetrahymena ciliary membranes were prepared by 4 different techniques, and their protein composition was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), EM and 2-dimensional thin-layer peptide mapping. Extraction of the isolated cilia by nonionic detergent solubilized the ciliary membranes but left the axonemal microtubules and dynein arms intact, as determined by quantitative EM. The proteins solubilized by detergent included a major 55,000-dalton protein, 1-3 high MW proteins that comigrated, on SDS-PAGE, with the axonemal dynein, as well as several other proteins of 45,000-50,000 daltons. Each of the major proteins contained a small amount of carbohydrate, as determined by PAS[periodic acid-Schiff]-staining; no PAS-positive material was detected in the detergent-extracted axonemes. The major 55,000-dalton protein has proteins quite similar to those of tubulin, based on SDS-PAGE using 3 different buffer systems as well as 2-dimensional maps of tryptic peptides from the isolated 55,000-dalton protein. To determine whether this tubulin-like protein was associated with the membrane or whether it was an axonemal or matrix protein released by detergent treatment, 3 different methods to isolate ciliary membrane vesicles were developed. The protein composition of each of these different vesicle preparations was the same as that of the detergent-solubilized material. A major ciliary membrane protein probably has properties similar to those of tubulin.