SMIM20
Small integral membrane protein 20
Also known as: C4orf52, MITRAC7, PNX, SIM20_HUMAN
Cross-references: UniProt · Ensembl · Human Protein Atlas · GeneCards · NCBI Gene
Protein identityUniProt · HPA
- UniProt accession
- Q8N5G0
- Gene
- SMIM20
- Ensembl
- ENSG00000250317
- Chromosome
- 4
- Canonical length
- 67 aa
- Protein class
- Predicted membrane proteins, Predicted secreted proteins
- Subcellular location
- Nucleoplasm,Nucleoli,Cytosol
- Secretome location
- Secreted to blood
OverviewNCBI Gene
Involved in mitochondrial cytochrome c oxidase assembly. Located in mitochondrial inner membrane. [provided by Alliance of Genome Resources, Jul 2025]
Canonical amino-acid sequenceUniProt
67 residues, UniProt reviewed canonical sequence.
>Q8N5G0|SMIM20
1 MSRNLRTALI FGGFISLIGA AFYPIYFRPL MRLEEYKKEQ AINRAGIVQE DVQPPGLKVW
61 SDPFGRKLocalizationUniProt · AlphaFold · HPA
Whether an antibody against SMIM20 can act on the native protein depends on physical access: surface and secreted proteins are reachable by circulating antibodies, intracellular proteins usually are not.
- Antibody reachability
- Secreted
- Secreted
- Yes
- Transmembrane segments
- 1
- Mean surface accessibility (rSASA)
- 0.49
- Highest tissue expression
- 92 nTPM
Expression across tissuesHPA
Tissue
- skeletal muscle: 92 nTPM
- epididymis: 72 nTPM
- tongue: 60 nTPM
- kidney: 54 nTPM
- choroid plexus: 47 nTPM
- heart muscle: 45 nTPM
Single-cell type
- epididymal principal cells: 221 nCPM
- parietal cells: 134 nCPM
- kupffer cells: 119 nCPM
- enterocytes: 116 nCPM
- decidual stromal cells: 98 nCPM
- plasma cells: 92 nCPM
Immune cell
- naive CD4 T-cell: 52 nTPM
- naive B-cell: 50 nTPM
- memory B-cell: 49 nTPM
- T-reg: 44 nTPM
- naive CD8 T-cell: 42 nTPM
- plasmacytoid DC: 40 nTPM
Brain region
- choroid plexus: 23 nTPM
- white matter: 22 nTPM
- hypothalamus: 20 nTPM
- cerebellum: 19 nTPM
- spinal cord: 19 nTPM
- basal ganglia: 18 nTPM
Genetic constraint and essentialitygnomAD · DepMap
Does the body need this protein intact? Low LOEUF or a strong DepMap dependency means loss or blockade of the protein is likely to be felt.
- gnomAD LOEUF (loss-of-function intolerance)
- 1.1
- gnomAD pLI
- 0.58
- gnomAD missense Z
- 0.63
- DepMap mean gene effect
- 0.05
- DepMap dependency class
- none
Cancer expressionTCGA
Across TCGA tumor cohorts, this protein is over-expressed in roughly 4% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).
OntologyGO
Biological processes
Cellular components
Protein domainsUniProt · Pfam · InterPro
- MITRAC7/Phoenixin
- MITRAC7/Phoenixin family
KeywordsUniProt
InteractionsUniProt · HPA
Protein binding partners of SMIM20 in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.
Antibody and autoantibody relevanceSeroatlas analysis
Seroatlas reads SMIM20 as an antibody target. Whether an autoantibody or antibody against SMIM20 could matter depends on whether native SMIM20 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.
SMIM20 is annotated as secreted, so native SMIM20 circulates and is directly accessible to antibodies. Secreted and cell-surface proteins are the autoantibody targets most likely to act like drugs, blocking or depleting the native protein.
Annotation status
The present source text does not explicitly label SMIM20 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.
Loading the interactive Seroatlas protein explorer...