Seroatlas · Human Serome Atlas

TIMM21

Mitochondrial import inner membrane translocase subunit Tim21

Also known as: C18orf55, HSPC154, TIM21, TIM21_HUMAN

Cross-references: UniProt · Ensembl · Human Protein Atlas · GeneCards · NCBI Gene

Protein identityUniProt · HPA

UniProt accession: Q9BVV7
Gene: TIMM21
Ensembl: ENSG00000075336
Chromosome: 18
Canonical length: 248 aa
Protein class: Predicted intracellular proteins, Predicted membrane proteins

OverviewNCBI Gene

Involved in mitochondrial cytochrome c oxidase assembly; mitochondrial respiratory chain complex I assembly; and protein import into mitochondrial matrix. Located in mitochondrion. Part of TIM23 mitochondrial import inner membrane translocase complex. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

248 residues, UniProt reviewed canonical sequence.

>Q9BVV7|TIMM21
     1  MICTFLRAVQ YTEKLHRSSA KRLLLPYIVL NKACLKTEPS LRCGLQYQKK TLRPRCILGV
    61  TQKTIWTQGP SPRKAKEDGS KQVSVHRSQR GGTAVPTSQK VKEAGRDFTY LIVVLFGISI
   121  TGGLFYTIFK ELFSSSSPSK IYGRALEKCR SHPEVIGVFG ESVKGYGEVT RRGRRQHVRF
   181  TEYVKDGLKH TCVKFYIEGS EPGKQGTVYA QVKENPGSGE YDFRYIFVEI ESYPRRTIII
   241  EDNRSQDD

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against TIMM21 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: Other membrane
Secreted: No
Transmembrane segments: 1
Mean surface accessibility (rSASA): 0.51
Highest tissue expression: 48 nTPM

Expression across tissuesHPA

Tissue

skeletal muscle: 48 nTPM
heart muscle: 46 nTPM
tongue: 45 nTPM
basal ganglia: 22 nTPM
liver: 21 nTPM
midbrain: 20 nTPM

Single-cell type

erythrocyte progenitors: 43 nCPM
migrating cytotrophoblasts: 36 nCPM
cytotrophoblasts: 34 nCPM
esophageal basal cells: 34 nCPM
extravillous trophoblasts: 33 nCPM
thymic myoid cells: 29 nCPM

Immune cell

non-classical monocyte: 18 nTPM
naive CD8 T-cell: 18 nTPM
NK-cell: 17 nTPM
memory B-cell: 16 nTPM
plasmacytoid DC: 16 nTPM
intermediate monocyte: 16 nTPM

Brain region

cerebellum: 21 nTPM
cerebral cortex: 18 nTPM
white matter: 17 nTPM
basal ganglia: 17 nTPM
hypothalamus: 16 nTPM
medulla oblongata: 15 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): 1.15
gnomAD pLI: 0
gnomAD missense Z: 0.01
DepMap mean gene effect: 0.04
DepMap dependency class: selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 5% 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

Mitochondrial import inner membrane translocase subunit Tim21
Tim21 IMS domain superfamily
TIM21

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of TIMM21 in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.

COA3

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads TIMM21 as an antibody target. Whether an autoantibody or antibody against TIMM21 could matter depends on whether native TIMM21 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

TIMM21 is annotated as predominantly intracellular. Intracellular proteins are common autoantibody markers, becoming visible to the immune system after cell injury or altered processing, but are usually markers of disease rather than direct drivers.

Annotation status

The present source text does not explicitly label TIMM21 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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