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SMIM20 small integral membrane protein 20 [ Homo sapiens (human) ]

Gene ID: 389203, updated on 3-Mar-2026
Official Symbol
SMIM20provided by HGNC
Official Full Name
small integral membrane protein 20provided by HGNC
Primary source
HGNC:HGNC:37260
See related
Ensembl:ENSG00000250317 MIM:617465; AllianceGenome:HGNC:37260
Gene type
protein coding
RefSeq status
VALIDATED
Organism
Homo sapiens
Lineage
Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae; Homo
Also known as
PNX; C4orf52; MITRAC7
Summary
Involved in mitochondrial cytochrome c oxidase assembly. Located in mitochondrial inner membrane. [provided by Alliance of Genome Resources, Jul 2025]
Expression
Ubiquitous expression in kidney (RPKM 18.0), duodenum (RPKM 16.8) and 25 other tissues See more
Orthologs
all
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Try the new Transcripts and proteins table
See SMIM20 in Genome Data Viewer
Location:
4p15.2
Exon count:
3
Annotation release Status Assembly Chr Location
RS_2025_08 current GRCh38.p14 (GCF_000001405.40) 4 NC_000004.12 (25914220..25929812)
RS_2025_08 current T2T-CHM13v2.0 (GCF_009914755.1) 4 NC_060928.1 (25896311..25911902)
RS_2024_09 previous assembly GRCh37.p13 (GCF_000001405.25) 4 NC_000004.11 (25915842..25931434)

Chromosome 4 - NC_000004.12Genomic Context describing neighboring genes Neighboring gene uncharacterized LOC102723733 Neighboring gene uncharacterized LOC124900688 Neighboring gene ATAC-STARR-seq lymphoblastoid active region 21380 Neighboring gene SMIM20 antisense RNA 1 Neighboring gene H3K27ac-H3K4me1 hESC enhancer GRCh37_chr4:25915129-25915678 Neighboring gene ATAC-STARR-seq lymphoblastoid active region 21381 Neighboring gene ATAC-STARR-seq lymphoblastoid active region 21382 Neighboring gene ATAC-STARR-seq lymphoblastoid silent region 15329 Neighboring gene ATAC-STARR-seq lymphoblastoid active region 21383 Neighboring gene NANOG-H3K27ac hESC enhancer GRCh37_chr4:25994521-25995044 Neighboring gene ATAC-STARR-seq lymphoblastoid silent region 15330 Neighboring gene uncharacterized LOC124900689 Neighboring gene NANOG-H3K27ac-H3K4me1 hESC enhancer GRCh37_chr4:26031006-26031587 Neighboring gene OCT4-NANOG-H3K27ac-H3K4me1 hESC enhancer GRCh37_chr4:26031588-26032170 Neighboring gene ATAC-STARR-seq lymphoblastoid silent region 15331 Neighboring gene ATAC-STARR-seq lymphoblastoid silent region 15332 Neighboring gene ATAC-STARR-seq lymphoblastoid silent region 15333 Neighboring gene ATAC-STARR-seq lymphoblastoid active region 21384 Neighboring gene long intergenic non-protein coding RNA 2357 Neighboring gene ATAC-STARR-seq lymphoblastoid active region 21385 Neighboring gene ATAC-STARR-seq lymphoblastoid active region 21386 Neighboring gene ATAC-STARR-seq lymphoblastoid active region 21387

Go to nucleotide: Graphics FASTA GenBank

  • Project title: Tissue-specific circular RNA induction during human fetal development
  • Description: 35 human fetal samples from 6 tissues (3 - 7 replicates per tissue) collected between 10 and 20 weeks gestational time were sequenced using Illumina TruSeq Stranded Total RNA
  • BioProject: PRJNA270632
  • Publication: PMID 26076956
  • Analysis date: Mon Apr 2 22:54:59 2018

Related articles in PubMed

  1. SMIM20 promotes complex IV biogenesis and Ca(2+) signaling in mice heart. Boshnakovska A, et al. Cell Rep, 2025 Jun 24. PMID 40402744
  2. Phoenixin: A Newly Discovered Peptide with Multi-Functions. Yuan T, et al. Protein Pept Lett, 2017. PMID 28176660
  3. MITRAC7 Acts as a COX1-Specific Chaperone and Reveals a Checkpoint during Cytochrome c Oxidase Assembly. Dennerlein S, et al. Cell Rep, 2015 Sep 8. PMID 26321642
  4. Multiplexed kinase interactome profiling quantifies cellular network activity and plasticity. Golkowski M, et al. Mol Cell, 2023 Mar 2. PMID 36736316, Free PMC Article
  5. Quantitative high-confidence human mitochondrial proteome and its dynamics in cellular context. Morgenstern M, et al. Cell Metab, 2021 Dec 7. PMID 34800366, Free PMC Article

See all (14) citations in PubMed

GeneRIFs: Gene References Into Functions

What's a GeneRIF?
  1. MITRAC7 affects the biogenesis pathway by stabilizing newly synthesized COX1 in assembly intermediates, concomitantly preventing turnover.
    Title: MITRAC7 Acts as a COX1-Specific Chaperone and Reveals a Checkpoint during Cytochrome c Oxidase Assembly.
  2. SMIM20 (MITRAC7) is a COX1 specific chaperone which is necessary for cytochrome c oxidase biogenesis.
    Title: MITRAC7 Acts as a COX1-Specific Chaperone and Reveals a Checkpoint during Cytochrome c Oxidase Assembly.
Submit: New GeneRIF Correction

Find tests for this gene in the NIH Genetic Testing Registry (GTR)

Review eQTL and phenotype association data in this region using PheGenI

See variants in ClinVar

See studies and variants in dbVar

See Variation Viewer (GRCh37.p13)

Products Interactant Other Gene Complex Source Pubs Description

Homology

Gene Ontology Provided by GOA

Function Evidence Code Pubs
enables protein binding IPI
Inferred from Physical Interaction
more info
 PubMed 
Process Evidence Code Pubs
involved_in mitochondrial respiratory chain complex IV assembly IBA
Inferred from Biological aspect of Ancestor
more info
  
involved_in mitochondrial respiratory chain complex IV assembly IDA
Inferred from Direct Assay
more info
 PubMed 
involved_in mitochondrial respiratory chain complex IV assembly IEA
Inferred from Electronic Annotation
more info
  
Component Evidence Code Pubs
located_in extracellular region IEA
Inferred from Electronic Annotation
more info
  
located_in membrane IEA
Inferred from Electronic Annotation
more info
  
is_active_in mitochondrial inner membrane IBA
Inferred from Biological aspect of Ancestor
more info
  
located_in mitochondrial inner membrane IDA
Inferred from Direct Assay
more info
 PubMed 
located_in mitochondrial inner membrane IEA
Inferred from Electronic Annotation
more info
  
located_in mitochondrial inner membrane TAS
Traceable Author Statement
more info
  
located_in mitochondrion HTP PubMed 
Preferred Names
small integral membrane protein 20
Names
mitochondrial translation regulation assembly intermediate of cytochrome c oxidase protein of 7 kDa
phoenixin

NEW Try the new Transcript table

RefSeqs maintained independently of Annotated Genomes

These reference sequences exist independently of genome builds. Explain

These reference sequences are curated independently of the genome annotation cycle, so their versions may not match the RefSeq versions in the current genome build. Identify version mismatches by comparing the version of the RefSeq in this section to the one reported in Genomic regions, transcripts, and products above.

mRNA and Protein(s)

  1. NM_001145432.3 → NP_001138904.1  small integral membrane protein 20 isoform 1

    See identical proteins and their annotated locations for NP_001138904.1

    Status: VALIDATED

    Description
    Transcript Variant: This variant (1) represents the longer transcript and encodes the longer isoform (1).
    Source sequence(s)
    AC133961
    Consensus CDS
    CCDS47038.1
    UniProtKB/Swiss-Prot
    C9JYT8, Q8N5G0, Q9BRT5
    Related
    ENSP00000427407.2, ENST00000506197.3
    Conserved Domains (1) summary
    pfam15061
    Location:2 → 57
    DUF4538; Domain of unknown function (DUF4538)

  2. NM_001394130.1 → NP_001381059.1  small integral membrane protein 20 isoform 2

    Status: VALIDATED

    Source sequence(s)
    AC133961
    Consensus CDS
    CCDS93489.1
    UniProtKB/TrEMBL
    E5RH91
    Related
    ENSP00000429820.1, ENST00000514384.1
    Conserved Domains (1) summary
    pfam15061
    Location:2 → 37
    DUF4538; Domain of unknown function (DUF4538)

RefSeqs of Annotated Genomes: GCF_000001405.40-RS_2025_08

The following sections contain reference sequences that belong to a specific genome build. Explain

Reference GRCh38.p14 Primary Assembly

Genomic

  1. NC_000004.12 Reference GRCh38.p14 Primary Assembly

    Range
    25914220..25929812
    Download
    GenBank, FASTA, Sequence Viewer (Graphics)

Alternate T2T-CHM13v2.0

Genomic

  1. NC_060928.1 Alternate T2T-CHM13v2.0

    Range
    25896311..25911902
    Download
    GenBank, FASTA, Sequence Viewer (Graphics)
Nucleotide Protein
Heading Accession and Version
Protein Accession Links
GenPept Link UniProtKB Link
Q8N5G0.3 GenPept UniProtKB/Swiss-Prot:Q8N5G0

Gene LinkOut

The following LinkOut resources are supplied by external providers. These providers are responsible for maintaining the links.

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