IMP1/YMR150C Summary Help

Standard Name IMP1 1
Systematic Name YMR150C
Feature Type ORF, Verified
Description Catalytic subunit of mitochondrial inner membrane peptidase complex; required for maturation of mitochondrial proteins of the intermembrane space; complex contains two catalytic subunits (Imp1p and Imp2p that differ in substrate specificty) and Som1p (2, 3, 4 and see Summary Paragraph)
Also known as: PET-TS2858
Name Description Inner Membrane Protease 1
Chromosomal Location
ChrXIII:562528 to 561956 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Genetic position: 92 cM
Gene Ontology Annotations All IMP1 GO evidence and references
  View Computational GO annotations for IMP1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 1 genes
Classical genetics
Large-scale survey
19 total interaction(s) for 14 unique genes/features.
Physical Interactions
  • Affinity Capture-RNA: 1
  • Affinity Capture-Western: 1
  • PCA: 2
  • Reconstituted Complex: 1

Genetic Interactions
  • Dosage Rescue: 1
  • Negative Genetic: 1
  • Phenotypic Enhancement: 1
  • Phenotypic Suppression: 2
  • Positive Genetic: 5
  • Synthetic Growth Defect: 2
  • Synthetic Lethality: 2

Expression Summary
Length (a.a.) 190
Molecular Weight (Da) 21,433
Isoelectric Point (pI) 7.52
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXIII:562528 to 561956 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Genetic position: 92 cM
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..573 562528..561956 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 SGDIDS000004758

About mitochondrial import

While the mitochondrial genome encodes a handful of proteins, most of the hundreds of proteins that reside in the mitochondrion are encoded by nuclear genes, translated in the cytoplasm, and imported into mitochondria via a series of complex molecular machines (see 5, 6 for review). Many of the proteins imported into mitochondria are involved in respiration, which is not an essential process: S. cerevisiae is able to carry out either fermentative growth on carbon sources such as glucose, or respiratory growth on nonfermentable carbon sources such as glycerol and ethanol. However, since maintenance of the mitochondrial compartment is essential to life, mutations that completely disrupt mitochondrial import are lethal.

About the Inner Membrane Protease (IMP)

Most proteins undergo proteolytic processing upon import into mitochondria, and multiple proteases cleave different subsets of these proteins. The Inner Membrane Protease, IMP, processes some proteins that are translocated from the mitochondrial matrix into the intermembrane space. IMP consists of three subunits: Imp1p, Imp2p, and Som1p (3). Both Imp1p and Imp2p are catalytic subunits and share 25% identity, though each protein has distinct substrate specificities (2, 7, 8). Among the substrates of Imp1p are the precursors to NADH-cytochrome b5 reductase (Mcr1p), cytochrome b2 (Cyb2p), FAD-dependent glycerol-3-phosphate dehydrogenase (Gut2p), and the mitochondrially encoded subunit II of cytochrome c oxidase (Cox2p), while the only known substrate of Imp2p is cytochrome c1 (Cyt1p; 3, 9, 2, 10). In addition to its catalytic activity, Imp2p is also required for the stable expression of Imp1p (2). Som1p is a noncatalytic subunit that has been proposed to have a role in substrate recognition and correct functioning of Imp1p; it is required for processing of Cox2p and Mcr1p, and the som1 mutation reduces processing of Cyb2p (3).

Note: the name IMP1 has also been used to refer to GAL2/YLR081W, which encodes a galactose transporter on the plasma membrane.

Last updated: 2009-03-17 Contact SGD

References cited on this page View Complete Literature Guide for IMP1
1) Behrens M, et al.  (1991) Mitochondrial inner membrane protease 1 of Saccharomyces cerevisiae shows sequence similarity to the Escherichia coli leader peptidase. Mol Gen Genet 228(1-2):167-76
2) Nunnari J, et al.  (1993) A mitochondrial protease with two catalytic subunits of nonoverlapping specificities. Science 262(5142):1997-2004
3) Jan PS, et al.  (2000) Som1, a third component of the yeast mitochondrial inner membrane peptidase complex that contains Imp1 and Imp2. Mol Gen Genet 263(3):483-91
4) Luo W, et al.  (2006) Substrate specificity of inner membrane peptidase in yeast mitochondria. Mol Genet Genomics 275(5):431-6
5) Neupert W and Herrmann JM  (2007) Translocation of proteins into mitochondria. Annu Rev Biochem 76:723-49
6) Mokranjac D and Neupert W  (2009) Thirty years of protein translocation into mitochondria: unexpectedly complex and still puzzling. Biochim Biophys Acta 1793(1):33-41
7) Chen X, et al.  (1999) Signal peptides having standard and nonstandard cleavage sites can be processed by Imp1p of the mitochondrial inner membrane protease. J Biol Chem 274(53):37750-4
8) Pratje E and Guiard B  (1986) One nuclear gene controls the removal of transient pre-sequences from two yeast proteins: one encoded by the nuclear the other by the mitochondrial genome. EMBO J 5(6):1313-7
9) Esser K, et al.  (1996) SOM 1, a small new gene required for mitochondrial inner membrane peptidase function in Saccharomyces cerevisiae. Mol Gen Genet 252(4):437-45
10) Esser K, et al.  (2004) The mitochondrial IMP peptidase of yeast: functional analysis of domains and identification of Gut2 as a new natural substrate. Mol Genet Genomics 271(5):616-26