β-tubulin, β2-tubulin, β2 tubulin, B2t, β2
ß Tubulin85D - sperm tubulin - ß1 tubulin is found in mitotically active germ cells and all somatic parts of the testis - starting with early spermatocytes, the ß1 isotype is switched off and all microtubular arrays contain ß2 tubulin.
Gene model reviewed during 5.49
There is only one protein coding transcript and one polypeptide associated with this gene
Polypeptides were identified in wing imaginal discs and in the CME W2 wing imaginal disc cell line by 2D gel electrophoresis and by microsequencing.
Dimer of alpha and beta chains. A typical microtubule is a hollow water-filled tube with an outer diameter of 25 nm and an inner diameter of 15 nM. Alpha-beta heterodimers associate head-to-tail to form protofilaments running lengthwise along the microtubule wall with the beta-tubulin subunit facing the microtubule plus end conferring a structural polarity. Microtubules usually have 13 protofilaments but different protofilament numbers can be found in some organisms and specialized cells.
Click to get a list of regulatory features (enhancers, TFBS, etc.) and gene disruptions (point mutations, indels, etc.) within or overlapping Dmel\βTub85D using the Feature Mapper tool.
GBrowse - Visual display of RNA-Seq signalsView Dmel\βTub85D in GBrowse 2
Please Note This section lists cDNAs and ESTs that fall within the genomic extent of the gene model, which may include cDNAs and ESTs of genes within introns, or of overlapping genes. Please see GBrowse for alignment of the cDNAs and ESTs to the gene model.
For each fully sequenced cDNA the DGRC maintains various forms of the cDNA (e.g tagged or untagged) in several different host vectors for subsequent cloning and expression in Drosophila and Drosophila cell lines.
When Hvir\βt is coexpressed with βTub85D the moth isoform imposed the 16-protofilament structure, characteristic of that found in moth, on the corresponding subset of microtubules, which normally contain only 13-protofilament microtubules. This demonstrates the architecture of the microtubule cytoskeleton can be directed by a component of β-tubulin.
Sequence information in the internal variable region is important for morphological development of the axoneme microtubules. This domain acts in concert with the variable C-terminus and both are involved in determining some of the functional properties that are unique to a given β-tubulin isoform.
The correct tubulin protein levels in the male germ cells is investigated.
Analysis of truncated βTub85D products reveals that the carboxy terminus is required for the organization of microtubule suprastructures in spermatogenesis.
An 18bp element, DE1 (downstream element 1), present in the 5' untranslated region of βTub85D is required for enhanced mRNA stability during spermiogenesis. The function of this element is autonomous and is transferable also on other mRNAs.
Identified in 2D gels of CMW W2 wing imaginal disc cell proteins.
Altered pattern of βTub85D gene expression in neurogenic mutants indicates a role for the neurogenic genes in the development of most visceral and somatic muscles.
P-element mediated transformation studies suggest that βTub60D can support only a subset of the multiple functions normally performed by βTub85D. Coexpression of βTub60D and βTub85D in the male germ line allows spindles and all classes of cytoplasmic microtubules to assemble and function normally. However when βTub60D exceeds 20% of the total testis β-tubulin pool it acts in a dominant way to disrupt normal axoneme assembly.
An allele of αTub84B has been identified due to second site non-complementation of alleles (including a null allele) of βTub85D. The genetic interaction between βTub85D and αTub84B is based on the structural interaction between the protein products of each gene.
Tubulins are the main structural components of microtubules in mitotic and meiotic spindles, cilia, flagella, neural processes and the cytoskeleton; nontubulin proteins (MAPS or microtubule-associated proteins) are involved along with tubulins in the formation of specialized microtubules (Theurkauf, Baum, Bo and Wensink, 1986; Rudolph, Kimble, Hoyle, Subler and Raff, 1987). Tubulin proteins are found in a wide variety of species from unicellular organisms to man; their biochemical and molecular structure is highly conserved. The α- and β-subunits from different organisms can be combined in vitro into hybrid microtubule structures and there is a high level of primary amino acid sequence identity in the proteins (Sanchez, Natzle, Cleveland, Kirschner and McCarthy, 1980; Raff, 1984). In D.melanogaster, two multigene families, each made up of four members, code for α- and β-tubulins, each tubulin subunit being a 55,000 dalton polypeptide. The tubulin genes in each multigene family are dispersed in the second and/or third chromosomes rather than arranged in clusters. βTub85D is a structural gene for β-tubulin. It is transcribed into mRNA that is testis-specific; the mRNA is translated into a β-tubulin subunit that is involved in the formation of microtubules in the sperm tail axoneme, the cytoplasmic microtubules and the meiotic spindle (Kemphues, Kaufman, Raff and Raff, 1982; Fuller, Caulton, Hutchens, Kaufman and Raff, 1988). Only the microtubules of the mitotic spindle are not affected by a null mutation in βTub85D. The first mutant discovered, βTub85DD (Kemphues Raff, Kaufman and Raff, 1979; Kemphues, Raff, Raff and Kaufman, 1980; Kemphues, Kaufman, Raff and Raff, 1982; Kemphues, Kaufman, Raff and Raff, 1983), codes in males for an electrophoretic variant of β2-tubulin that causes disruption of microtubule function in all stages of spermatogenesis (beginning with meiosis) and shows abnormal spindle formation, abnormal chromosome movement and no cytokinesis. This phenotype is expressed in males in both homo- and heterozygotes; mutants heterozygous over wild type contain both wild-type and mutant β2-tubulins; mutants over a deficiency for the locus contain only mutant β2-tubulin. Severity of effect on meiosis is as follows: βTub85DD/βTub85DD > βTub85DD/+ > βTub85DD/+/+, the first two genotypes being sterile and the last weakly fertile. All females are fertile. Chromosome replication and condensation appear normal. Recessive male-sterile mutations have also been induced, two of them in βTub85DD chromosomes and the rest in βTub85D+ chromosomes. Testes of flies homozygous for the recessives βTub85D3, βTub85D4, βTub85DDrv1, and βTub85DDrv2 synthesize, but later degrade, both α-tubulin and β-tubulin and show abnormalities in meiotic divisions, nuclear shaping, and formation of the flagellar axoneme (Kemphues, Kaufman, Raff and Raff, 1982; Kemphues, Kaufman, Raff and Raff, 1983; Fuller, 1986). The most extreme recessive allele, βTub85Dn, is male sterile but female fertile when homozygous (Fuller, Caulton, Hutchens, Kaufman and Raff, 1988); heterozygotes raised at 25oC are male fertile, but those raised at 18oC are male sterile. Recessive alleles βTub85D6 - βTub85D10 seem to accumulate normal amounts of β-tubulin but the β-tubulin subunits are defective. βTub85D6, βTub85D7 and βTub85D8 cause different defects in spermatogenesis. βTub85D8 is unable to form normal closed microtubules (Fuller, Caulton, Hutchens, Kaufman and Raff, 1987); in homozygous males it is defective in meiosis, nuclear shaping, and flagellar elongation. This allele is semidominant; heterozygous males with one normal and one abnormal tubulin subunit, form some functional sperm. Transheterozygotes between ms(3)nc (second site non-complementing) mutations and certain βTub85D alleles are male sterile even if wild-type copies of both genes are present (Fuller, 1986); a deletion of a ms(3)nc mutation in a heterozygote over βTub85Dn, however, is fertile in males.