PMPCA

Mitochondrial-processing peptidase subunit alpha is an enzyme that in humans is encoded by the PMPCA gene.[5][6][7] This gene PMPCA encoded a protein that is a member of the peptidase M16 family. This protein is located in the mitochondrial matrix and catalyzes the cleavage of the leader peptides of precursor proteins newly imported into the mitochondria, though it only functions as part of a heterodimeric complex.

PMPCA
Identifiers
AliasesPMPCA, Alpha-MPP, INPP5E, P-55, SCAR2, peptidase, mitochondrial processing alpha subunit, CLA1, CPD3, peptidase, mitochondrial processing subunit alpha
External IDsOMIM: 613036 MGI: 1918568 HomoloGene: 6078 GeneCards: PMPCA
Gene location (Human)
Chr.Chromosome 9 (human)[1]
Band9q34.3Start136,410,641 bp[1]
End136,423,761 bp[1]
RNA expression pattern
More reference expression data
Orthologs
SpeciesHumanMouse
Entrez

23203

66865

Ensembl

ENSG00000165688

ENSMUSG00000026926

UniProt

Q10713
Q5SXN9

Q9DC61

RefSeq (mRNA)

NM_001282944
NM_001282946
NM_015160

NM_173180

RefSeq (protein)

NP_001269873
NP_001269875
NP_055975

NP_775272

Location (UCSC)Chr 9: 136.41 – 136.42 MbChr 2: 26.39 – 26.4 Mb
PubMed search[3][4]
Wikidata
View/Edit HumanView/Edit Mouse


Structure

The Mitochondrial-processing peptidase subunit alpha precursor protein is 58.2 KDa in size and composed of 525 amino acids. The precursor protein contains a 33 amino acid N-terminal fragment as mitochondrion targeting sequence. After cleavage, the matured PMPCA protein is 54.6 KDa in size and has a theoretical pI of 5.88.

Function

Mitochondrial-processing peptidase (MPP) is a metalloendopeptidase, containing two structurally related subunits, Subunit alpha and mitochondrial-processing peptidase subunit beta, working in conjunction for its catalytic function.[8] Containing the catalytic site, the beta subunit PMPCB protein cleaves presequences (transit peptides) from mitochondrial protein precursors and releases of N-terminal transit peptides from precursor proteins imported into the mitochondrion, typically with Arg in position P2.

Interactions

As the alpha subunit of Mitochondrial-processing peptidase, PMPCA forms a heterodimer with the subunit PMPCB.

Clinical significance

The majority of mitochondrial proteins is nuclear-coded, which necessitates proper translocations of mitochondrial targeting proteins. Many mitochondrial proteins are synthesized in a precursor form that contains mitochondria targeting sequence. These precursors are usually cleaved by peptidases and proteases before they arrive their sub-organellar locations. It is likely that altered activity of the mitochondrial processing peptidases is essential to ensure the correct maturation of mitochondrial proteins and that altered activity of these proteases will have dramatic effects in the activity, stability and assembly of mitochondrial proteins. Evidences showed that MPP was involved in the proteolytic maturation of Frataxin, a protein responsible for iron homeostasis.[9] Accordingly, MPP deficiency was shown to be involved in Friedreich ataxia, an autossomic recessive neurodegenerative disorder[10][11]

References

  1. GRCh38: Ensembl release 89: ENSG00000165688 - Ensembl, May 2017
  2. GRCm38: Ensembl release 89: ENSMUSG00000026926 - Ensembl, May 2017
  3. "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. Nagase T, Seki N, Tanaka A, Ishikawa K, Nomura N (Mar 1996). "Prediction of the coding sequences of unidentified human genes. IV. The coding sequences of 40 new genes (KIAA0121-KIAA0160) deduced by analysis of cDNA clones from human cell line KG-1". DNA Res. 2 (4): 167–74, 199–210. doi:10.1093/dnares/2.4.167. PMID 8590280.
  6. Nagase T, Miyajima N, Tanaka A, Sazuka T, Seki N, Sato S, Tabata S, Ishikawa K, Kawarabayasi Y, Kotani H, et al. (Jul 1995). "Prediction of the coding sequences of unidentified human genes. III. The coding sequences of 40 new genes (KIAA0081-KIAA0120) deduced by analysis of cDNA clones from human cell line KG-1". DNA Res. 2 (1): 37–43. doi:10.1093/dnares/2.1.37. PMID 7788527.
  7. "Entrez Gene: PMPCA peptidase (mitochondrial processing) alpha".
  8. Teixeira PF, Glaser E (Feb 2013). "Processing peptidases in mitochondria and chloroplasts". Biochimica et Biophysica Acta (BBA) - Molecular Cell Research. 1833 (2): 360–70. doi:10.1016/j.bbamcr.2012.03.012. PMID 22495024.
  9. Branda SS, Yang ZY, Chew A, Isaya G (Jun 1999). "Mitochondrial intermediate peptidase and the yeast frataxin homolog together maintain mitochondrial iron homeostasis in Saccharomyces cerevisiae". Human Molecular Genetics. 8 (6): 1099–110. doi:10.1093/hmg/8.6.1099. PMID 10332043.
  10. Cavadini P, Adamec J, Taroni F, Gakh O, Isaya G (Dec 2000). "Two-step processing of human frataxin by mitochondrial processing peptidase. Precursor and intermediate forms are cleaved at different rates". The Journal of Biological Chemistry. 275 (52): 41469–75. doi:10.1074/jbc.M006539200. PMID 11020385.
  11. Patel PI, Isaya G (Jul 2001). "Friedreich ataxia: from GAA triplet-repeat expansion to frataxin deficiency". American Journal of Human Genetics. 69 (1): 15–24. doi:10.1086/321283. PMC 1226030. PMID 11391483.

Further reading


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