Seroatlas · Human Serome Atlas

TTC21A

Tetratricopeptide repeat protein 21A

Also known as: IFT139A, STI2, Thm2, TT21A_HUMAN

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

Protein identityUniProt · HPA

UniProt accession
Q8NDW8
Gene
TTC21A
Ensembl
ENSG00000168026
Chromosome
3
Canonical length
1320 aa
Protein class
Disease related genes, Human disease related genes, Predicted intracellular proteins
Subcellular location
Nucleoplasm

OverviewNCBI Gene

Involved in flagellated sperm motility and spermatid development. Predicted to be located in cilium. Predicted to be part of intraciliary transport particle A. Implicated in spermatogenic failure 37. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

1320 residues, UniProt reviewed canonical sequence.

>Q8NDW8|TTC21A
     1  MSSNDSSLMA GIIYYSQEKY FHHVQQAAAV GLEKFSNDPV LKFFKAYGVL KEEHIQDAIS
    61  DLESIRHHPD VSLCSTMALI YAHKRCEIID REAIQELEYS LKEIRKTVSG TALYYAGLFL
   121  WLIGRHDKAK EYIDRMLKIS RGFREAYVLR GWVDLTSDKP HTAKKAIEYL EQGIQDTKDV
   181  LGLMGKAMYF MMQQNYSEAL EVVNQITVTS GSFLPALVLK MQLFLARQDW EQTVEMGHRI
   241  LEKDESNIDA CQILTVHELA REGNMTTVSS LKTQKATNHV RNLIKALETR EPENPSLHLK
   301  KIIVVSRLCG SHQVILGLVC SFIERTFMAT PSYVHVATEL GYLFILKNQV KEALLWYSEA
   361  MKLDKDGMAG LTGIILCHIL EGHLEEAEYR LEFLKEVQKS LGKSEVLIFL QALLMSRKHK
   421  GEEETTALLK EAVELHFSSM QGIPLGSEYF EKLDPYFLVC IAKEYLLFCP KQPRLPGQIV
   481  SPLLKQVAVI LNPVVKAAPA LIDPLYLMAQ VRYYSELENA QSILQRCLEL DPASVDAHLL
   541  MCQIYLAQGN FGMCFHCLEL GVSHNFQVRD HPLYHLIKAR ALNKAGDYPE AIKTLKMVIK
   601  LPALKKEEGR KFLRPSVQPS QRASILLELV EALRLNGELH EATKVMQDTI NEFGGTPEEN
   661  RITIANVDLV LSKGNVDVAL NMLRNILPKQ SCYMEAREKM ANIYLQTLRD RRLYIRCYRE
   721  LCEHLPGPHT SLLLGDALMS ILEPEKALEV YDEAYRQNPH DASLASRIGH AYVKAHQYTE
   781  AIEYYEAAQK INGQDFLCCD LGKLLLKLKK VNKAEKVLKQ ALEHDIVQDI PSMMNDVKCL
   841  LLLAKVYKSH KKEAVIETLN KALDLQSRIL KRVPLEQPEM IPSQKQLAAS ICIQFAEHYL
   901  AEKEYDKAVQ SYKDVFSYLP TDNKVMLELA QLYLLQGHLD LCEQHCAILL QTEQNHETAS
   961  VLMADLMFRK QKHEAAINLY HQVLEKAPDN FLVLHKLIDL LRRSGKLEDI PAFFELAKKV
  1021  SSRVPLEPGF NYCRGIYCWH IGQPNEALKF LNKARKDSTW GQSAIYHMVQ ICLNPDNEVV
  1081  GGEAFENQGA ESNYMEKKEL EQQGVSTAEK LLREFYPHSD SSQTQLRLLQ GLCRLATREK
  1141  ANMEAALGSF IQIAQAEKDS VPALLALAQA YVFLKQIPKA RMQLKRLAKT PWVLSEAEDL
  1201  EKSWLLLADI YCQGSKFDLA LELLRRCVQY NKSCYKAYEY MGFIMEKEQS YKDAVTNYKL
  1261  AWKYSHHANP AIGFKLAFNY LKDKKFVEAI EICNDVLREH PDYPKIREEI LEKARRSLRP

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against TTC21A 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
Intracellular
Secreted
No
Transmembrane segments
0
Mean surface accessibility (rSASA)
0.25
Highest tissue expression
43 nTPM

Expression across tissuesHPA

Tissue

  • testis: 43 nTPM
  • fallopian tube: 7 nTPM
  • tonsil: 1.5 nTPM
  • pancreas: 1.2 nTPM
  • cervix: 1 nTPM
  • lung: 0.9 nTPM

Single-cell type

  • respiratory ciliated cells: 256 nCPM
  • late primary spermatocytes: 161 nCPM
  • ependymal cells: 156 nCPM
  • fallopian tube ciliated cells: 132 nCPM
  • late spermatids: 132 nCPM
  • early spermatids: 128 nCPM

Immune cell

  • memory B-cell: 0.7 nTPM
  • naive B-cell: 0.7 nTPM
  • intermediate monocyte: 0.4 nTPM
  • classical monocyte: 0.2 nTPM
  • neutrophil: 0.1 nTPM
  • plasmacytoid DC: 0.1 nTPM

Brain region

  • choroid plexus: 7.5 nTPM
  • midbrain: 5.8 nTPM
  • spinal cord: 4.5 nTPM
  • medulla oblongata: 4.2 nTPM
  • pons: 3.7 nTPM
  • basal ganglia: 3.3 nTPM

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about TTC21A.

Disease | AllUniProt

Conditions TTC21A is implicated in, by any mechanism.

Disease | GeneticClinVar

10 pathogenic / likely-pathogenic of 274 ClinVar records.

Conditions with pathogenic or likely-pathogenic variants.

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)
0.88
gnomAD pLI
0
gnomAD missense Z
0.95
DepMap mean gene effect
0.18
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

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of TTC21A 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 TTC21A as an antibody target. Whether an autoantibody or antibody against TTC21A could matter depends on whether native TTC21A is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

TTC21A 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 TTC21A as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/TTC21A. Study-independent annotations aggregated from UniProt, Human Protein Atlas, PubMed, IEDB, Pfam, InterPro, Gene Ontology, AlphaFold, gnomAD, DepMap, ClinVar, TCGA. Catalog release seroatlas-reviewed-human-uniprot-20260313.

Seroatlas is the reference for exploring autoantibody and antibody serology at the human-protein level: the autoreactome and human serome, multiplex serology (HuProt, HuScan, VirScan, PhIP-Seq).

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