TIM54/YJL054W Summary Help

Standard Name TIM54 1
Systematic Name YJL054W
Feature Type ORF, Verified
Description Component of the mitochondrial TIM22 complex; involved in insertion of polytopic proteins into the inner membrane (1, 2, 3, 4, 5, 6 and see Summary Paragraph)
Name Description Translocase of the Inner Mitochondrial membrane
Chromosomal Location
ChrX:334265 to 335701 | ORF Map | GBrowse
Gene Ontology Annotations All TIM54 GO evidence and references
  View Computational GO annotations for TIM54
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 2 genes
Classical genetics
Large-scale survey
reduction of function
26 total interaction(s) for 13 unique genes/features.
Physical Interactions
  • Affinity Capture-RNA: 2
  • Affinity Capture-Western: 13
  • PCA: 1
  • Reconstituted Complex: 2

Genetic Interactions
  • Dosage Rescue: 5
  • Negative Genetic: 1
  • Synthetic Lethality: 2

Expression Summary
Length (a.a.) 478
Molecular Weight (Da) 54,182
Isoelectric Point (pI) 5.58
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrX:334265 to 335701 | ORF Map | GBrowse
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1437 334265..335701 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 SGDIDS000003590

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 7, 8 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 TIM22 complex

The TIM22 complex of the mitochondrial inner membrane mediates the insertion of large hydrophobic proteins, typically transporters (carrier proteins) with multiple transmembrane segments, into the inner membrane. These proteins travel through the outer membrane via the translocase of the outer mitochondrial membrane (TOM) complex. Their transit across the intermembrane space to the TIM22 complex in the inner membrane is mediated by complexes of small soluble protein chaperones: Tim8p with Tim13p, and Tim9p with Tim10p. The membrane-embedded core of the TIM22 complex consists of Tim54p, Tim22p, Tim18p, and Sdh3p (9); additionally, the small Tim proteins Tim9p, Tim10p, and Tim12p are associated with the complex on the intermembrane space side (reviewed in 10, 8).

about TIM54

TIM54 encodes a component of the membrane-embedded core of the TIM22 complex (1, 5), but the exact function of Tim54p is unclear. The gene was originally shown to be essential for viability (1), but in subsequent studies viable null mutants were obtained, although showing greatly reduced import activity of the TIM22 complex (11, 12). The null mutant is also petite-negative, meaning that it cannot survive loss of the mitochondrial genome (12). Tim54p appears to play an accessory role in the stability and/or assembly of the TIM22 complex (1, 11). It was also shown to be required for the assembly of Yme1p into the inner membrane protease complex even though Yme1p is imported via the TIM23 complex, thus suggesting a role for Tim54p in mitochondrial protein turnover (12).

Last updated: 2009-03-17 Contact SGD

References cited on this page View Complete Literature Guide for TIM54
1) Kerscher O, et al.  (1997) The Tim54p-Tim22p complex mediates insertion of proteins into the mitochondrial inner membrane. J Cell Biol 139(7):1663-75
2) Kerscher O, et al.  (2000) Tim18p is a new component of the Tim54p-Tim22p translocon in the mitochondrial inner membrane. Mol Biol Cell 11(1):103-16
3) Koehler CM, et al.  (2000) Tim18p, a new subunit of the TIM22 complex that mediates insertion of imported proteins into the yeast mitochondrial inner membrane. Mol Cell Biol 20(4):1187-93
4) Jensen RE and Dunn CD  (2002) Protein import into and across the mitochondrial inner membrane: role of the TIM23 and TIM22 translocons. Biochim Biophys Acta 1592(1):25-34
5) Rehling P, et al.  (2003) Protein insertion into the mitochondrial inner membrane by a twin-pore translocase. Science 299(5613):1747-51
6) Rehling P, et al.  (2003) Insertion of hydrophobic membrane proteins into the inner mitochondrial membrane--a guided tour. J Mol Biol 326(3):639-57
7) Neupert W and Herrmann JM  (2007) Translocation of proteins into mitochondria. Annu Rev Biochem 76:723-49
8) 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
9) Gebert N, et al.  (2011) Dual Function of Sdh3 in the Respiratory Chain and TIM22 Protein Translocase of the Mitochondrial Inner Membrane. Mol Cell 44(5):811-8
10) Bolender N, et al.  (2008) Multiple pathways for sorting mitochondrial precursor proteins. EMBO Rep 9(1):42-9
11) Kovermann P, et al.  (2002) Tim22, the essential core of the mitochondrial protein insertion complex, forms a voltage-activated and signal-gated channel. Mol Cell 9(2):363-73
12) Hwang DK, et al.  (2007) Tim54p connects inner membrane assembly and proteolytic pathways in the mitochondrion. J Cell Biol 178(7):1161-75