Psychiatry related information on betaTub85D

• The polarity of kinesin's motor activity can be reversed by MT disassembly and interactions between a motor and a MT end can either slow or speed the rate of tubulin depolymerization [1].

High impact information on betaTub85D

• In most of these embryos, however, centrosomes continue to migrate in a coordinated manner to the cortex, where they reorganize tubulin, actin, and the overlying plasma membrane [2].
• Each of these mutations encodes a variant beta 2-tubulin subunit synthesized at normal levels, but which is subsequently unstable and rapidly degraded within the testis [3].
• The testis-specific beta-tubulin subunit in Drosophila melanogaster has multiple functions in spermatogenesis [3].
• The expression of beta 3-tubulin is accompanied by a coordinate transient increase in the level of synthesis of the embryonic alpha-tubulins, thereby maintaining an approximately equimolar synthesis of alpha- and beta-tubulin subunits throughout embryogenesis [4].
• The extent of these defects in microtubule function depends on the dosage of the B2tD mutation, being most severe in males homozygous for the mutation, intermediate in males heterozygous for the mutation, and least marked in males heterozygous for B2tD and a tandem duplication of the region of the genome containing the B2t locus [5].

Biological context of betaTub85D

• Tubulin sorting during dimerization in vivo [6].
• When beta1 exceeded beta2, however, axonemes with 10 doublets were produced, an alteration unprecedented in natural phylogeny [7].
• We have determined the complete nucleotide sequences coding for the beta 1 and beta 2 tubulins of Drosophila melanogaster and the beta 2 tubulin of D. hydei, and found these insect beta tubulins to be highly conserved and like beta tubulins of other organisms [8].
• Mutations responsible for different classes of functional phenotypes are distributed throughout the beta 2-tubulin molecule [9].
• We therefore conclude that the amino acid sequence of the beta 2-tubulin internal variable region is required for generation of correct axoneme morphology but not for general microtubule functions [9].

Anatomical context of betaTub85D

• Once dimers are formed, no further sorting occurs during microtubule assembly: alpha-beta 2 Delta C dimers are incorporated into axonemes in proportion to their contribution to the total dimer pool [6].
• Thus, differences in organelle assembly reside in beta-tubulin [7].
• In the testes the beta 2 tubulin participates in different microtubules as shown by genetic analysis (Kemphues et al. 1982) [8].
• The auxiliary beta subunits do not form the ion conducting pore, yet play important roles in channel modulation and plasma membrane expression. beta1 and beta2 are transmembrane proteins with one extracellular V-set immunoglobulin (Ig) protein domain [10].
• The best of all worlds or the best possible world? Developmental constraint in the evolution of beta-tubulin and the sperm tail axoneme [11].

Associations of betaTub85D with chemical compounds

• These results are discussed in terms of a model in which beta-ecdysone affects the distribution of tubulin in "assembly-active" and "assembly-inactive" pools [12].
• The genomic DNA sequence and deduced amino acid sequence are presented for three Drosophila melanogaster beta-tubulins: a developmentally regulated isoform beta 3-tubulin, the wild-type testis-specific isoform beta 2-tubulin, and an ethyl methanesulfonate-induced assembly-defective mutation of the testis isoform, B2t8 [13].
• The maximum response of the SAD beta 2 nicotinic receptor to clothianidin was larger than that observed for acetylcholine [14].
• To compare the actions of clothianidin, a neonicotinoid acting on insect nicotinic acetylcholine receptors, and related compounds with that of imidacloprid, the compounds were tested on the Drosophila SAD-chicken beta2 nicotinic acetylcholine receptor expressed in Xenopus laevis oocytes using two-electrode voltage-clamp electrophysiology [14].

Other interactions of betaTub85D

• In Drosophila, these organelles contain distinct but similar beta-tubulin isoforms [4-10]: basal bodies contain only beta1-tubulin, and only beta2-tubulin is used for assembly of sperm axonemes [7].
• Tests of fecundity in males that coexpress beta 2 and the chimeric beta 3 beta 2C protein showed that in Drosophila there are differential requirements for sperm motility in the male and in the female reproductive tract [15].
• Probes representing two multigene families (beta-tubulin and yolk-protein) hybridized as would be expected if all sites had been conserved in the two species on the same chromosomal elements [16].
• In the present study we show that rat brain beta1 and beta2, but not alphaIIA, subunits interact in a trans-homophilic fashion, resulting in recruitment of the cytoskeletal protein ankyrin to sites of cell-cell contact in transfected Drosophila S2 cells [10].
• Functional constraint underlies 60 million year stasis of Dipteran testis-specific beta-tubulin [17].

Analytical, diagnostic and therapeutic context of betaTub85D

• In order to further characterize these tubulin complexes, DEAE Sepharose chromatography, Sephacryl S-300 size exclusion columns and specific immunoprecipitation were used [18].
• Moreover, studies on affinity chromatography of the purified 4 kDa C-terminal tubulin peptide bound to an affinity column, confirmed that DMAP-85 interacts directly with this regulatory domain on tubulin subunits [19].
• We have used saturation binding and electron microscopy to examine the interaction of the kinesin motor domain with the microtubule surface and found that binding saturated at one kinesin head per tubulin heterodimer [20].
• Testes from these males were shown, by two-dimensional gel electrophoresis, to contain both the normal testis-specific beta-tubulin and an electrophoretic variant of this tubulin in equal amounts [21].
• Sequence analysis shows that beta 2 tubulin is only 83% identical to the two beta tubulins expressed in amoebae [22].

References