ANB1/YJR047C Summary Help

Standard Name ANB1 1
Systematic Name YJR047C
Alias HYP1 , TIF51B 2
Feature Type ORF, Verified
Description Translation elongation factor eIF-5A; previously thought to function in translation initiation; undergoes an essential hypusination modification; expressed under anaerobic conditions; ANB1 has a paralog, HYP2, that arose from the whole genome duplication (2, 3, 4, 5, 6 and see Summary Paragraph)
Also known as: eIF5A , eIF-5A 2
Name Description ANaeroBically induced 1
Chromosomal Location
ChrX:525381 to 524908 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All ANB1 GO evidence and references
  View Computational GO annotations for ANB1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 11 genes
Classical genetics
Large-scale survey
37 total interaction(s) for 35 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 2
  • Co-fractionation: 1
  • Co-purification: 1
  • Protein-RNA: 1
  • Reconstituted Complex: 6
  • Two-hybrid: 2

Genetic Interactions
  • Dosage Rescue: 1
  • Negative Genetic: 12
  • Phenotypic Enhancement: 1
  • Positive Genetic: 5
  • Synthetic Growth Defect: 3
  • Synthetic Lethality: 1
  • Synthetic Rescue: 1

Expression Summary
Length (a.a.) 157
Molecular Weight (Da) 17,131
Isoelectric Point (pI) 4.65
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrX:525381 to 524908 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..474 525381..524908 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 SGDIDS000003808

The paralogous genes HYP2 and ANB1 encode the translation elongation factor eIF-5A. The two gene products are 90% identical to each other (2). Because Hyp2p is expressed under normal, aerobic growth conditions while Anb1p is expressed only under anaerobic conditions, most functional studies have focused on Hyp2p (7, 2). However, since the two proteins are functionally interchangeable in vivo (3), results obtained with Hyp2p are likely to be directly applicable to Anb1p.

eIF-5A was long considered to be a translation initiation factor based on in vitro assays of certain aspects of translation; however, since some in vitro assays did not suggest a role in initiation, and since depletion of eIF-5A does not severely affect overall translation, its role was unclear (see 8, 6 for review). Since then, detailed studies of hyp2 conditional mutant phenotypes have revealed translational defects and alterations in polysome profiles characteristic of elongation factor mutations, as well as decreased accumulation of P-bodies, which is known to occur in elongation mutants (9, 6). HYP2 also displays synthetic genetic interactions with translation elongation factor mutants (9), and physical interaction with elongation factor eEF2 (Eft1p and Eft2p; 10). Furthermore, Hyp2p stimulates both translation elongation and termination in vitro (6). Thus, multiple lines of evidence are consistent with a primary role for eIF-5A in promoting translation elongation (9, 6).

eIF-5A is highly conserved across all species. The human ortholog EIF5A (OMIM) complements the inviability of the yeast hyp2 anb1 double null mutant (3). Both Hyp2p and Anb1p undergo the conversion of a single lysine residue to hypusine (N- epsilon-(4-amino-2-hydroxybutyl)-lysine), which is essential for function (11, 12). The modification is conserved among eIF-5A orthologs in eukaryotes and Archaea, and eIF-5A orthologs are the only known hypusinated proteins (13). eIF-5A orthologs in Eubacterial species, such as elongation factor P (EF-P), are not hypusinated (13). Hypusination of Hyp2p is essential for two kinds of protein-protein interactions in which it participates: homodimer formation; and binding to intact 80S ribosomes, with a preference for actively translating ribosomes (14, 15). Both Hyp2p and Anb1p are also phosphorylated on a serine residue, but this modification has no obvious effects on function (4, 16).

The hyp2 null mutant in strain W303 is inviable under standard (aerobic) conditions although growth is observed under anaerobic conditions due to ANB1 expression; conversely, the anb1 null mutant fails to grow under anaerobic conditions but has no apparent phenotype under aerobic conditions (7). The hyp2 null mutant is slow-growing, rather than inviable, under standard conditions in a different strain background (2). The hyp2 anb1 double null mutant is inviable under all conditions (2).

Transcription of ANB1 is tightly regulated by the presence of oxygen, and ANB1 has been studied extensively as an example of an anaerobically expressed gene. Anb1p is undetectable under aerobic conditions (7), and its mRNA is 200-fold more abundant in the absence of oxygen than in its presence (17). Transcriptional repression of ANB1 under aerobic conditions is mediated by the transcription factors Rox1p and Mot3p, which cooperate to recruit the Cyc8p-Tup1p general co-repressor complex to the ANB1 promoter (17, 18, 19).

Last updated: 2009-08-31 Contact SGD

References cited on this page View Complete Literature Guide for ANB1
1) Lowry CV and Zitomer RS  (1984) Oxygen regulation of anaerobic and aerobic genes mediated by a common factor in yeast. Proc Natl Acad Sci U S A 81(19):6129-33
2) Schnier J, et al.  (1991) Translation initiation factor 5A and its hypusine modification are essential for cell viability in the yeast Saccharomyces cerevisiae. Mol Cell Biol 11(6):3105-14
3) Schwelberger HG, et al.  (1993) Translation initiation factor eIF-5A expressed from either of two yeast genes or from human cDNA. Functional identity under aerobic and anaerobic conditions. J Biol Chem 268(19):14018-25
4) Kang HA, et al.  (1993) Translation initiation factor eIF-5A, the hypusine-containing protein, is phosphorylated on serine in Saccharomyces cerevisiae. J Biol Chem 268(20):14750-6
5) 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
6) Saini P, et al.  (2009) Hypusine-containing protein eIF5A promotes translation elongation. Nature 459(7243):118-21
7) Wohl T, et al.  (1993) The HYP2 gene of Saccharomyces cerevisiae is essential for aerobic growth: characterization of different isoforms of the hypusine-containing protein Hyp2p and analysis of gene disruption mutants. Mol Gen Genet 241(3-4):305-11
8) Merrick W  (2009) Translation: Till termination us do part. Nature 459(7243):44-5
9) Gregio AP, et al.  (2009) eIF5A has a function in the elongation step of translation in yeast. Biochem Biophys Res Commun 380(4):785-90
10) Zanelli CF, et al.  (2006) eIF5A binds to translational machinery components and affects translation in yeast. Biochem Biophys Res Commun 348(4):1358-66
11) Park MH  (2006) The post-translational synthesis of a polyamine-derived amino acid, hypusine, in the eukaryotic translation initiation factor 5A (eIF5A). J Biochem (Tokyo) 139(2):161-9
12) Dias CA, et al.  (2008) Structural modeling and mutational analysis of yeast eukaryotic translation initiation factor 5A reveal new critical residues and reinforce its involvement in protein synthesis. FEBS J 275(8):1874-88
13) Wolff EC, et al.  (2007) Posttranslational synthesis of hypusine: evolutionary progression and specificity of the hypusine modification. Amino Acids 33(2):341-50
14) Gentz PM, et al.  (2009) Dimerization of the yeast eukaryotic translation initiation factor 5A requires hypusine and is RNA dependent. FEBS J 276(3):695-706
15) Jao DL and Chen KY  (2006) Tandem affinity purification revealed the hypusine-dependent binding of eukaryotic initiation factor 5A to the translating 80S ribosomal complex. J Cell Biochem 97(3):583-98
16) Klier H, et al.  (1993) Determination and mutational analysis of the phosphorylation site in the hypusine-containing protein Hyp2p. FEBS Lett 334(3):360-4
17) Klinkenberg LG, et al.  (2005) Combinatorial repression of the hypoxic genes of Saccharomyces cerevisiae by DNA binding proteins Rox1 and Mot3. Eukaryot Cell 4(4):649-60
18) Lowry CV and Zitomer RS  (1988) ROX1 encodes a heme-induced repression factor regulating ANB1 and CYC7 of Saccharomyces cerevisiae. Mol Cell Biol 8(11):4651-8
19) Lowry CV and Lieber RH  (1986) Negative regulation of the Saccharomyces cerevisiae ANB1 gene by heme, as mediated by the ROX1 gene product. Mol Cell Biol 6(12):4145-8