Microheterogeneity of alpha and beta subunit of tubulin from microtubules of starfish (Asterias amurensis) sperm flagella

Reduced and alkylated tubulin, obtained by aqueous extraction of an acetone powder of axonemes of starfish sperm flagella, was separated into two peaks of protein by column chromatography on urea/hydroxylapatite with a linear gradient of sodium phosphate (2 mm to 250 mm, pH 6.5). Sodium dodecyl sulfate/ polyacrylamide gel electrophoresis indicated that the first peak mainly consisted of α-subunit, while the second was β-subunit of tubulin. Furthermore, when analyzed by gel isoelectric focusing, α and β-subunit were resolved into four distinct bands, respectively. These bands appeared between the pH range of 5.5 to 6.0 and never overlapped.