OCH1/YGL038C Summary Help

Standard Name OCH1 1
Systematic Name YGL038C
Alias NGD29 , LDB12
Feature Type ORF, Verified
Description Mannosyltransferase of the cis-Golgi apparatus; initiates the polymannose outer chain elongation of N-linked oligosaccharides of glycoproteins (2, 3, 4 and see Summary Paragraph)
Name Description Outer CHain elongation 1
Chromosomal Location
ChrVII:426804 to 425362 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Genetic position: -31.86 cM
Gene Ontology Annotations All OCH1 GO evidence and references
  View Computational GO annotations for OCH1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 8 genes
Classical genetics
Large-scale survey
22 total interaction(s) for 20 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 1
  • Affinity Capture-Western: 1
  • Co-fractionation: 1
  • Co-localization: 1
  • PCA: 1

Genetic Interactions
  • Dosage Lethality: 1
  • Negative Genetic: 1
  • Phenotypic Enhancement: 2
  • Synthetic Growth Defect: 4
  • Synthetic Lethality: 8
  • Synthetic Rescue: 1

Expression Summary
Length (a.a.) 480
Molecular Weight (Da) 55,155
Isoelectric Point (pI) 7.85
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrVII:426804 to 425362 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Genetic position: -31.86 cM
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1443 426804..425362 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 | E.C. | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000003006

During N-linked glycosylation of proteins, oligosaccharide chains are assembled on the carrier molecule dolichyl pyrophosphate in the following order: 2 molecules of N-acetylglucosamine (GlcNAc), 9 molecules of mannose, and 3 molecules of glucose. These 14-residue oligosaccharide cores are then transferred to asparagine residues on nascent polypeptide chains in the endoplasmic reticulum (ER). As proteins progress through the Golgi apparatus, the oligosaccharide cores are modified by trimming and extension to generate a diverse array of glycosylated proteins (reviewed in 5, 6).

Och1p adds a mannose moiety to core N-linked oligosaccharides upon their arrival in the Golgi apparatus; this is the last modification before the N-linked glycosylation pathway forks to produce either large mannan outer chains or small core-type oligosaccharides (reviewed in 7). Och1p is a membrane-bound (2, 8, 9) alpha-1,6-mannosyltransferase (2, 8, 9, 10) of the cis-Golgi cisternae (3, 10), but it is recycled between the trans-Golgi network (3, 11) and a late compartment of the ER (12). Despite its homology to and partial complementation of S. pombe och1(+) (13), S. cerevisiae Och1p is not a component of the alpha-1,6-mannosyltransferase complex. OCH1 expression is regulated by SKN7 (14, 15), SLN1 (14, 15), and CDC4 (16).

Deletion or depletion of OCH1 causes lethality or slow-growth (2, 1, 9). och1 mutants cannot form high mannose oligosaccharides (~50+ mannose residues) (2, 1, 8, 9) so they have decreased levels of cell wall mannoproteins (1, 17), causing weakness and defects in bud formation (1, 8, 17) and hypersensitivity to agents that attack the cell wall (calcofluor white, hygromycin B, and SDS) (17). Weakening of cell walls in hypotonic solution can be partially suppressed by the addition of osmotic stabilizers such as salt or sorbitol (17, 18).

Last updated: 2005-07-12 Contact SGD

References cited on this page View Complete Literature Guide for OCH1
1) Nagasu T, et al.  (1992) Isolation of new temperature-sensitive mutants of Saccharomyces cerevisiae deficient in mannose outer chain elongation. Yeast 8(7):535-47
2) Nakayama K, et al.  (1992) OCH1 encodes a novel membrane bound mannosyltransferase: outer chain elongation of asparagine-linked oligosaccharides. EMBO J 11(7):2511-9
3) Harris SL and Waters MG  (1996) Localization of a yeast early Golgi mannosyltransferase, Och1p, involves retrograde transport. J Cell Biol 132(6):985-98
4) Romero PA, et al.  (1994) Glycoprotein biosynthesis in Saccharomyces cerevisiae. Partial purification of the alpha-1,6-mannosyltransferase that initiates outer chain synthesis. Glycobiology 4(2):135-40
5) Herscovics A and Orlean P  (1993) Glycoprotein biosynthesis in yeast. FASEB J 7(6):540-50
6) Burda P and Aebi M  (1999) The dolichol pathway of N-linked glycosylation. Biochim Biophys Acta 1426(2):239-57
7) Munro S  (2001) What can yeast tell us about N-linked glycosylation in the Golgi apparatus? FEBS Lett 498(2-3):223-7
8) Nakanishi-Shindo Y, et al.  (1993) Structure of the N-linked oligosaccharides that show the complete loss of alpha-1,6-polymannose outer chain from och1, och1 mnn1, and och1 mnn1 alg3 mutants of Saccharomyces cerevisiae. J Biol Chem 268(35):26338-45
9) Lehle L, et al.  (1995) Glycoprotein biosynthesis in Saccharomyces cerevisiae: ngd29, an N-glycosylation mutant allelic to och1 having a defect in the initiation of outer chain formation. FEBS Lett 370(1-2):41-5
10) Gaynor EC, et al.  (1994) Signal-mediated retrieval of a membrane protein from the Golgi to the ER in yeast. J Cell Biol 127(3):653-65
11) Bruinsma P, et al.  (2004) Retrograde transport of the mannosyltransferase Och1p to the early Golgi requires a component of the COG transport complex. J Biol Chem 279(38):39814-23
12) Karhinen L and Makarow M  (2004) Activity of recycling Golgi mannosyltransferases in the yeast endoplasmic reticulum. J Cell Sci 117(Pt 2):351-8
13) Yoko-o T, et al.  (2001) Schizosaccharomyces pombe och1(+) encodes alpha-1,6-mannosyltransferase that is involved in outer chain elongation of N-linked oligosaccharides. FEBS Lett 489(1):75-80
14) Horecka J and Sprague GF  (2000) Use of imidazoleglycerolphosphate dehydratase (His3) as a biological reporter in yeast. Methods Enzymol 326():107-19
15) Li S, et al.  (2002) The eukaryotic two-component histidine kinase Sln1p regulates OCH1 via the transcription factor, Skn7p. Mol Biol Cell 13(2):412-24
16) Cui Z, et al.  (2002) Cdc4 is involved in the transcriptional control of OCH1, a gene encoding alpha-1,6-mannosyltransferase in Saccharomyces cerevisiae. Yeast 19(1):69-77
17) Lee BN and Elion EA  (1999) The MAPKKK Ste11 regulates vegetative growth through a kinase cascade of shared signaling components. Proc Natl Acad Sci U S A 96(22):12679-84
18) Cullen PJ, et al.  (2000) Defects in protein glycosylation cause SHO1-dependent activation of a STE12 signaling pathway in yeast. Genetics 155(3):1005-18