Tubulin is the major constituent of microtubules, a cylinder consisting of laterally associated linear protofilaments composed of alpha- and beta-tubulin heterodimers. Microtubules grow by the addition of GTP-tubulin dimers to the microtubule end, where a stabilizing cap forms. Below the cap, tubulin dimers are in GDP-bound state, owing to GTPase activity of alpha-tubulin.

(UniProt, Q24560)

A structural gene for β-tubulin. Its mRNA is maternally stored in the oocytes and expressed in the nurse cells and in early embryos (Natzle and McCarthy, 1984; Gasch et al., 1988); at this stage, the transcripts are evenly distributed throughout the embryo, but later in development they are concentrated in the primordia of the nervous system and their derivatives (the supra-oesophageal ganglion and ventral nerve cord) and in the visceral mesoderm. Since βTub56D is expressed throughout development and in all adult tissues (Rudolph et al., 1987), βTub56D tubulin is probably involved in all the microtubular structures necessary for cell division and cell shape (Raff et al., 1982; Biolojan et al., 1984). It is the major β-tubulin of adult flies in all structures except the testis.