PIM1/YBL022C Summary Help

Standard Name PIM1 1
Systematic Name YBL022C
Feature Type ORF, Verified
Description ATP-dependent Lon protease; involved in degradation of misfolded proteins in mitochondria; required for biogenesis and maintenance of mitochondria (1, 2, 3 and see Summary Paragraph)
Name Description Proteolysis In Mitochondria 4
Chromosomal Location
ChrII:181275 to 177874 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All PIM1 GO evidence and references
  View Computational GO annotations for PIM1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 8 genes
Classical genetics
Large-scale survey
73 total interaction(s) for 71 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 18
  • Affinity Capture-RNA: 2
  • Affinity Capture-Western: 3

Genetic Interactions
  • Dosage Rescue: 3
  • Negative Genetic: 28
  • Phenotypic Suppression: 1
  • Positive Genetic: 9
  • Synthetic Growth Defect: 6
  • Synthetic Lethality: 3

Expression Summary
Length (a.a.) 1,133
Molecular Weight (Da) 127,111
Isoelectric Point (pI) 5.36
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrII:181275 to 177874 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 2011-02-03 | Sequence: 1997-01-28
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..3402 181275..177874 2011-02-03 1997-01-28
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
Retired NameLON1
Primary SGDIDS000000118

PIM1 encodes the ATP-dependent Lon protease (1, 3). It is required for degradation of misfolded or mislocalized proteins or of unassembled subunits in the mitochondrial matrix with the assistance of chaperone proteins such as Hsp70 (encoded by SSC1) and Hsp78 (2, 5, 6, 7). Note that the mitochondrion contains at least two other ATP-dependent proteases, the m-AAA protease consisting of two subunits (Afg3p and Yta12p) and the i-AAA protease (encoded by the YME1 gene), both of which are involved in proteolysis of mitochondrial inner membrane proteins (8, 9).

Cells with null mutations in pim1 are viable, but have abnormal mitochondrial morphology, lose mitochondrial DNA, and are respiratory deficient, being unable to grow on non-fermentable carbon sources such as glycerol, ethanol, or lactate (1, 3). In addition to its catalytic activity as a protease, Pim1p may also play a role in the assembly of mitochondrial complexes. Overexpression of protease-defective Pim1p suppresses the respiratory growth and respiratory complex assembly defects of cells lacking either of the two subunits of mitochondrial membrane m-AAA protease, Afg3p and Yta12p, while overexpression of protease-capable but ATPase-defective Pim1p does not, implicating the ATPase activity in a chaperone-like function for respiratory complexes (8). However, pim1 mutants also have defects in the stability of the intron-containing COX1 and COB pre-mRNAs and in the translation of COX1 mRNA, so it may be that Pim1p is involved in the production of these two subunits, perhaps via proteolytic maturation of an intron-encoded mRNA maturase, rather than in their assembly into respiratory complexes (10, 9).

Lon protease is conserved in bacteria, archaea, and eukaryotic mitochondria and peroxisomes (7). In cerevisiae, the Lon protease is composed of a ring of seven Pim1p subunits (11), while in E. coli the ring is composed of six identical subunits (7). Each subunit contains two conserved domains, a central ATPase domain and a carboxyl-terminal domain containing proteolytic activity (7), in contrast to the arrangement in two-component ATP-dependent proteases such as the 26S proteasome where the ATPase and proteolytic activities are present in different subunits (7).

Last updated: 2009-03-03 Contact SGD

References cited on this page View Complete Literature Guide for PIM1
1) Van Dyck L, et al.  (1994) PIM1 encodes a mitochondrial ATP-dependent protease that is required for mitochondrial function in the yeast Saccharomyces cerevisiae. J Biol Chem 269(1):238-42
2) Wagner I, et al.  (1994) Molecular chaperones cooperate with PIM1 protease in the degradation of misfolded proteins in mitochondria. EMBO J 13(21):5135-45
3) Suzuki CK, et al.  (1994) Requirement for the yeast gene LON in intramitochondrial proteolysis and maintenance of respiration. Science 264(5156):273-6
4) Major T, et al.  (2006) Proteomic analysis of mitochondrial protein turnover: identification of novel substrate proteins of the matrix protease pim1. Mol Cell Biol 26(3):762-76
5) von Janowsky B, et al.  (2005) Structural properties of substrate proteins determine their proteolysis by the mitochondrial AAA+ protease Pim1. Biol Chem 386(12):1307-17
6) Rottgers K, et al.  (2002) The ClpB homolog Hsp78 is required for the efficient degradation of proteins in the mitochondrial matrix. J Biol Chem 277(48):45829-37
7) Lee I and Suzuki CK  (2008) Functional mechanics of the ATP-dependent Lon protease- lessons from endogenous protein and synthetic peptide substrates. Biochim Biophys Acta 1784(5):727-35
8) Rep M, et al.  (1996) Promotion of mitochondrial membrane complex assembly by a proteolytically inactive yeast Lon. Science 274(5284):103-6
9) Van Dyck L and Langer T  (1999) ATP-dependent proteases controlling mitochondrial function in the yeast Saccharomyces cerevisiae. Cell Mol Life Sci 56(9-10):825-42
10) van Dyck L, et al.  (1998) The ATP-dependent PIM1 protease is required for the expression of intron-containing genes in mitochondria. Genes Dev 12(10):1515-24
11) Stahlberg H, et al.  (1999) Mitochondrial Lon of Saccharomyces cerevisiae is a ring-shaped protease with seven flexible subunits. Proc Natl Acad Sci U S A 96(12):6787-90