TUB1/YML085C Summary Help

Standard Name TUB1
Systematic Name YML085C
Feature Type ORF, Verified
Description Alpha-tubulin; associates with beta-tubulin (Tub2p) to form tubulin dimer, which polymerizes to form microtubules; relative distribution to nuclear foci increases upon DNA replication stress; TUB1 has a paralog, TUB3, that arose from the whole genome duplication (1, 2, 3 and see Summary Paragraph)
Name Description TUBulin
Chromosomal Location
ChrXIII:99400 to 97941 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Genetic position: -62 cM
Gene Ontology Annotations All TUB1 GO evidence and references
  View Computational GO annotations for TUB1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 2 genes
Classical genetics
Large-scale survey
177 total interaction(s) for 115 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 60
  • Affinity Capture-RNA: 1
  • Affinity Capture-Western: 8
  • Co-crystal Structure: 4
  • Co-fractionation: 1
  • Co-localization: 7
  • Co-purification: 3
  • Reconstituted Complex: 7
  • Two-hybrid: 11

Genetic Interactions
  • Dosage Lethality: 3
  • Dosage Rescue: 18
  • Phenotypic Enhancement: 4
  • Phenotypic Suppression: 4
  • Synthetic Growth Defect: 25
  • Synthetic Haploinsufficiency: 1
  • Synthetic Lethality: 15
  • Synthetic Rescue: 5

Expression Summary
Length (a.a.) 447
Molecular Weight (Da) 49,800
Isoelectric Point (pI) 4.81
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXIII:99400 to 97941 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Genetic position: -62 cM
Last Update Coordinates: 1996-07-31 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..25 99400..99376 1996-07-31 1996-07-31
Intron 26..141 99375..99260 1996-07-31 1996-07-31
CDS 142..1460 99259..97941 1996-07-31 1996-07-31
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000004550

In S.cerevisiae, two genes encode alpha-tubulin: TUB1 and TUB3 (4, 1). Tub1p belongs to the tubulin superfamily, which includes beta- and gamma-tubulin and the prokaryotic tubulin-like gene FtsZ (reviewed in 5, 6). Alpha- and beta-tubulin form tubulin heterodimers, which polymerize into microtubules. Microtubules are conserved cytoskeletal elements that function in nuclear processes: chromosome segregation in mitosis and meiosis, spindle orientation, and nuclear migration during mitosis and mating (7; for reviews, see 8, 9). All microtubules in S.cerevisiae emanate from a microtubule organizing center called the spindle pole body (SPB), which is embedded in the nuclear envelope (for review, see 10). Microtubules extend from both faces of the SPB, generating two types of microtubules: nuclear and cytoplasmic microtubules (11; for review, see 10). The distribution and length of these two types of microtubules is regulated throughout the cell cycle (11; reviewed in 12).

TUB1 and TUB3 were cloned based on their strong homology with their counterparts in other eukaryotes (4, 1). TUB1 is essential and more highly expressed than TUB3 (4, 1). TUB1 and TUB3 are functionally equivalent; consequently, TUB3 overexpression can suppress the lethality of a tub1 null mutation (1). However, in vitro experiments suggest functional differences since microtubules purified from cells that contain only Tub1p are more dynamic than those that contain only Tub3p, displaying elevated rates of shrinkage and catastrophe (13). There is an abundance of tub1 conditional mutants resulting from genetic screens for chromosome loss and sensitivity or resistance to anti-microtubule drugs, suppressor analysis, as well as in vitro mutagenesis (14, 15, 16, 17). Almost all conditional tub1 mutants are cold sensitive, presumably reflecting the intrinsic cold sensitivity of the microtubule polymer. Tub1p interacts with numerous proteins involved in the regulation of microtubules, such as microtubule motors, SPB components, kinetochore components, tubulin biogenesis factors, and beta-tubulin (Tub2p) (reviewed in 8, 9).

Tub1p is a GTP-binding protein, though the GTP bound to Tub1p (and Tub3p) is non-hydrolyzable, whereas the GTP bound to Tub2p is hydrolyzed following tubulin dimer addition to the microtubule end (18). The structure of tubulin has been crystallized in the polymerized state; Tub1p (and Tub3p), rather than Tub2p, is believed to interact directly with the SPB (19).

Last updated: 2003-12-18 Contact SGD

References cited on this page View Complete Literature Guide for TUB1
1) Schatz PJ, et al.  (1986) Genetically essential and nonessential alpha-tubulin genes specify functionally interchangeable proteins. Mol Cell Biol 6(11):3722-33
2) Byrne KP and Wolfe KH  (2005) The Yeast Gene Order Browser: combining curated homology and syntenic context reveals gene fate in polyploid species. Genome Res 15(10):1456-61
3) Tkach JM, et al.  (2012) Dissecting DNA damage response pathways by analysing protein localization and abundance changes during DNA replication stress. Nat Cell Biol 14(9):966-76
4) Schatz PJ, et al.  (1986) Two functional alpha-tubulin genes of the yeast Saccharomyces cerevisiae encode divergent proteins. Mol Cell Biol 6(11):3711-21
5) McKean PG, et al.  (2001) The extended tubulin superfamily. J Cell Sci 114(Pt 15):2723-33
6) Nogales E, et al.  (1998) Tubulin and FtsZ form a distinct family of GTPases. Nat Struct Biol 5(6):451-8
7) Jacobs CW, et al.  (1988) Functions of microtubules in the Saccharomyces cerevisiae cell cycle. J Cell Biol 107(4):1409-26
8) Winsor B and Schiebel E  (1997) Review: an overview of the Saccharomyces cerevisiae microtubule and microfilament cytoskeleton. Yeast 13(5):399-434
9) Botstein D, et al.  (1997) "The yeast cytoskeleton." Pp. 1-90 in The Molecular and Cellular Biology of the Yeast Saccharomyces: Cell Cycle and Cell Biology, edited by Pringle JR, Broach JR and Jones EW. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press
10) Knop M, et al.  (1999) Microtubule organization by the budding yeast spindle pole body. Biol Cell 91(4-5):291-304
11) Kilmartin JV and Adams AE  (1984) Structural rearrangements of tubulin and actin during the cell cycle of the yeast Saccharomyces. J Cell Biol 98(3):922-33
12) Carminati JL and Stearns T  (1999) Cytoskeletal dynamics in yeast. Methods Cell Biol 58:87-105
13) Bode CJ, et al.  (2003) The two alpha-tubulin isotypes in budding yeast have opposing effects on microtubule dynamics in vitro. EMBO Rep 4(1):94-9
14) Hoyt MA, et al.  (1990) Chromosome instability mutants of Saccharomyces cerevisiae that are defective in microtubule-mediated processes. Mol Cell Biol 10(1):223-34
15) Stearns T, et al.  (1990) Yeast mutants sensitive to antimicrotubule drugs define three genes that affect microtubule function. Genetics 124(2):251-62
16) Schatz PJ, et al.  (1988) Isolation and characterization of conditional-lethal mutations in the TUB1 alpha-tubulin gene of the yeast Saccharomyces cerevisiae. Genetics 120(3):681-95
17) Richards KL, et al.  (2000) Structure-function relationships in yeast tubulins. Mol Biol Cell 11(5):1887-903
18) Carlier MF and Pantaloni D  (1981) Kinetic analysis of guanosine 5'-triphosphate hydrolysis associated with tubulin polymerization. Biochemistry 20(7):1918-24
19) Nogales E, et al.  (1999) High-resolution model of the microtubule. Cell 96(1):79-88