TUB3/YML124C Summary Help

Standard Name TUB3
Systematic Name YML124C
Feature Type ORF, Verified
Description Alpha-tubulin; associates with beta-tubulin (Tub2p) to form tubulin dimer, which polymerizes to form microtubules; expressed at lower level than Tub1p; TUB3 has a paralog, TUB1, that arose from the whole genome duplication (1, 2 and see Summary Paragraph)
Name Description TUBulin
Chromosomal Location
ChrXIII:23683 to 22048 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Genetic position: -101 cM
Gene Ontology Annotations All TUB3 GO evidence and references
  View Computational GO annotations for TUB3
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 3 genes
Classical genetics
Large-scale survey
287 total interaction(s) for 160 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 47
  • Affinity Capture-RNA: 3
  • Affinity Capture-Western: 3
  • Co-localization: 1
  • Reconstituted Complex: 1
  • Two-hybrid: 4

Genetic Interactions
  • Dosage Rescue: 7
  • Negative Genetic: 146
  • Phenotypic Enhancement: 1
  • Positive Genetic: 13
  • Synthetic Growth Defect: 15
  • Synthetic Lethality: 42
  • Synthetic Rescue: 4

Expression Summary
Length (a.a.) 445
Molecular Weight (Da) 49,694
Isoelectric Point (pI) 4.92
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXIII:23683 to 22048 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Genetic position: -101 cM
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..25 23683..23659 2011-02-03 1996-07-31
Intron 26..323 23658..23361 2011-02-03 1996-07-31
CDS 324..1636 23360..22048 2011-02-03 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 SGDIDS000004593

In S.cerevisiae, two genes encode alpha-tubulin: TUB1 and TUB3 (3, 1). Tub3p belongs to the tubulin superfamily, which includes beta- and gamma-tubulin and the prokaryotic tubulin-like gene FtsZ (reviewed in 4, 5). 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 (6; for reviews, see 7, 8). 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 9). Microtubules extend from both faces of the SPB, generating two types of microtubules: nuclear and cytoplasmic microtubules (10; for review, see 9). Distribution and length of these two types of microtubules is regulated throughout the cell cycle 10, (reviewed in 11).

TUB1 and TUB3 were cloned based on strong homology with their counterparts in other eukaryotes (3, 1). It is not clear why S. cerevisiae has two functionally identical genes for alpha-tubulin, but this arrangement may have some significance since it is conserved in the fission yeast, S. pombe (12). However, in vitro experiments suggest there are functional differences, as microtubules containing Tub3p as the sole alpha tubulin are less dynamic than wild-type microtubules (reduced shrinkage and catastrophe rates) while those containing Tub1p are more dynamic than wild-type (13). Relative to TUB1, TUB3 is expressed at low levels and is not essential for growth (1). Further, overexpression of TUB3 can suppress the lethality of a tub1 null mutation (1). tub3 null mutants grow normally under most conditions but are benomyl- (an anti-microtubule drug) and cold-sensitive (1). Tub3p 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 7, 8).

Tub3p is a GTP-binding protein, though the GTP bound to Tub3p (and Tub1p) is non-hydrolyzable, whereas the GTP bound to Tub2p is hydrolyzed following tubulin dimer addition to the microtubule end (14). The structure of tubulin has been crystallized in the polymerized state; Tub3p (and Tub1p), rather than Tub2p, is believed to interact directly with the SPB (15).

Last updated: 2003-12-18 Contact SGD

References cited on this page View Complete Literature Guide for TUB3
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) 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
4) McKean PG, et al.  (2001) The extended tubulin superfamily. J Cell Sci 114(Pt 15):2723-33
5) Nogales E, et al.  (1998) Tubulin and FtsZ form a distinct family of GTPases. Nat Struct Biol 5(6):451-8
6) Jacobs CW, et al.  (1988) Functions of microtubules in the Saccharomyces cerevisiae cell cycle. J Cell Biol 107(4):1409-26
7) Winsor B and Schiebel E  (1997) Review: an overview of the Saccharomyces cerevisiae microtubule and microfilament cytoskeleton. Yeast 13(5):399-434
8) 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
9) Knop M, et al.  (1999) Microtubule organization by the budding yeast spindle pole body. Biol Cell 91(4-5):291-304
10) 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
11) Carminati JL and Stearns T  (1999) Cytoskeletal dynamics in yeast. Methods Cell Biol 58:87-105
12) Adachi Y, et al.  (1986) Differential expressions of essential and nonessential alpha-tubulin genes in Schizosaccharomyces pombe. Mol Cell Biol 6(6):2168-78
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) Carlier MF and Pantaloni D  (1981) Kinetic analysis of guanosine 5'-triphosphate hydrolysis associated with tubulin polymerization. Biochemistry 20(7):1918-24
15) Nogales E, et al.  (1999) High-resolution model of the microtubule. Cell 96(1):79-88