Expression of a new β tubulin subunit is induced by 20-hydroxyecdysone in drosophila cultured cells

Abstract One polypeptide, P4, of molecular weight 55000 daltons and pHi, 5,1, is synthesized in Drosophila melanogaster Kc 0 % cells only when they were treated by the insect moulting hormone, 20 hydroxyecdysone (20-HE). P4 is precipitated with vinblastine sulfate and migrates as a tubulin subunit. Immunoblot experiment confirms that P4 is a β subunit of tubulin. This β tubulin is recovered by in vitro translation only when mRNAs are extracted from treated cells. Thus, regulation of expression of this polypeptide is at the level of transcripts and is under a steroid hormone control. The 20-HE induced β tubulin comigrates with the β3 subunit and like the latter, is specific to the mid period of embryogenesis.