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Reviewed, UniProtKB/Swiss-Prot P05164 (PERM_HUMAN)

Last modified September 2, 2008. Version 110. Feed History...

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Names and origin · Protein attributes · General annotation (Comments) · Ontologies · Alternative products · Sequence annotation (Features) · Sequences · References · Web resources · Cross-references · Entry information · Relevant documents

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Names and origin

Protein namesRecommended name:
    Myeloperoxidase
      Short name=MPO
    EC=1.11.1.7
Cleaved into the following 4 chains:
    1- Recommended name:
            89 kDa myeloperoxidase
    2- Recommended name:
            84 kDa myeloperoxidase
    3- Recommended name:
            Myeloperoxidase light chain
    4- Recommended name:
            Myeloperoxidase heavy chain
Gene names
Name: MPO
OrganismHomo sapiens (Human)
Taxonomic identifier9606 [NCBI]
Taxonomic lineageEukaryota › Metazoa › Chordata › Craniata › Vertebrata › Euteleostomi › Mammalia › Eutheria › Euarchontoglires › Primates › Haplorrhini › Catarrhini › Hominidae › Homo

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Protein attributes

Sequence length745 AA.
Sequence statusComplete.
Sequence processingThe displayed sequence is further processed into a mature form.
Protein existenceEvidence at protein level.

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General annotation (Comments)

Function

Part of the host defense system of polymorphonuclear leukocytes. It is responsible for microbicidal activity against a wide range of organisms. In the stimulated PMN, MPO catalyzes the production of hypohalous acids, primarily hypochlorous acid in physiologic situations, and other toxic intermediates that greatly enhance PMN microbicidal activity.

Catalytic activity

Donor + H(2)O(2) = oxidized donor + 2 H(2)O.

Cl(-) + H(2)O(2) = HOCl + 2 H(2)O.

Cofactor

Binds 1 calcium ion per heterodimer.

Binds 1 heme B (iron-protoporphyrin IX) group covalently per heterodimer.

Subunit structure

Tetramer of two light chains and two heavy chains.

Subcellular location

Lysosome.

Involvement in disease

Defects in MPO are the cause of myeloperoxidase deficiency (MPD) [MIM:254600]. MPD is an autosomal recessive defect that results in disseminated candidiasis.

Sequence similarities

Belongs to the peroxidase family. XPO subfamily.

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Ontologies

Keywords

   Biological processHydrogen peroxide
   Cellular componentLysosome
   Coding sequence diversityAlternative splicing
Polymorphism
   DiseaseDisease mutation
   DomainSignal
   LigandCalcium
Heme
Iron
Metal-binding
   Molecular functionOxidoreductase
Peroxidase
   PTMGlycoprotein
Oxidation
   Technical term3D-structure
Direct protein sequencing

Gene Ontology (GO)

   Biological processanti-apoptosis

Traceable author statement. Source: ProtInc

defense response Ref.20

Traceable author statement. Source: ProtInc

response to oxidative stress Ref.6

Traceable author statement. Source: UniProtKB

   Cellular componentlysosome Ref.20

Traceable author statement. Source: ProtInc

nucleus

Traceable author statement. Source: ProtInc

   Molecular functionchromatin binding

Traceable author statement. Source: ProtInc

peroxidase activity

Traceable author statement. Source: ProtInc

Complete GO annotation...

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Alternative products

This entry describes 3 isoforms produced by alternative splicing. [Align] [Select]
Isoform H17 (identifier: P05164-1)

Also known as: B;

This isoform has been chosen as the 'canonical' sequence. All positional information in this entry refers to it. This is also the sequence that appears in the downloadable versions of the entry.
Isoform H14 (identifier: P05164-2)

The sequence of this isoform differs from the canonical sequence as follows:
     1-95: Missing.
Isoform H7 (identifier: P05164-3)

Also known as: A;

The sequence of this isoform differs from the canonical sequence as follows:
     182-182: N → NRCGWLGVAAGTGLREASRTPQASRCQRPVLPC

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Sequence annotation (Features)

Feature keyPosition(s)LengthDescriptionGraphical view

Molecule processing

Signal peptide1 – 4848
Chain49 – 74569789 kDa myeloperoxidase
Propeptide49 – 164116
Chain155 – 74559184 kDa myeloperoxidase
Chain165 – 745581Myeloperoxidase
Chain165 – 278114Myeloperoxidase light chain
Chain279 – 745467Myeloperoxidase heavy chain

Sites

Active site2611Proton acceptor
Metal binding2621Calcium
Metal binding3341Calcium
Metal binding3361Calcium; via carbonyl oxygen
Metal binding3381Calcium
Metal binding3401Calcium
Metal binding5021Iron (heme axial ligand)
Binding site2601Heme (covalent; via 3 links)
Binding site4081Heme (covalent; via 3 links)
Binding site4091Heme (covalent; via 3 links)
Site4051Transition state stabilizer

Amino acid modifications

Modified residue3161Cysteine sulfenic acid (-SOH)
Glycosylation1391N-linked (GlcNAc...)
Glycosylation3231N-linked (GlcNAc...)
Glycosylation3551N-linked (GlcNAc...)
Glycosylation3911N-linked (GlcNAc...)
Glycosylation4831N-linked (GlcNAc...)
Disulfide bond167 ↔ 180
Disulfide bond281 ↔ 291
Disulfide bond285 ↔ 309
Disulfide bond319Interchain
Disulfide bond387 ↔ 398
Disulfide bond606 ↔ 663
Disulfide bond704 ↔ 730

Natural variations

Alternative sequence1 – 9595Missing in isoform H14.
Alternative sequence1821N → NRCGWLGVAAGTGLREASRT PQASRCQRPVLPC in isoform H7.
Natural variant531V → F: dbSNP rs7208693.
Natural variant1731Y → C in MPD; affects proteolytic processing and secretion.
Natural variant2511M → T in MPD.
Natural variant4471R → Q in a colorectal cancer sample; somatic mutation.
Natural variant5691R → W in MPD; suppress post-translational processing.
Natural variant6041R → C
Natural variant6831E → Q
Natural variant7171I → V: dbSNP rs2759.

Experimental info

Sequence conflict361L → V Ref.3 Ref.4

Secondary structure

1 .............................................................................................. 745
Helix Strand Turn

Details...