Seroatlas · Human Serome Atlas

DDX21

Nucleolar RNA helicase 2

Also known as: DDX21_HUMAN, GURDB, RH-II/GU

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

Protein identityUniProt · HPA

UniProt accession
Q9NR30
Gene
DDX21
Ensembl
ENSG00000165732
Chromosome
10
Canonical length
783 aa
Protein class
Enzymes, Plasma proteins, Predicted intracellular proteins
Subcellular location
Nucleoplasm,Nucleoli rim,Mitotic chromosome
Quaternary structure
Homodimer

OverviewNCBI Gene

DEAD box proteins, characterized by the conserved motif Asp-Glu-Ala-Asp (DEAD), are putative RNA helicases. They are implicated in a number of cellular processes involving alteration of RNA secondary structure such as translation initiation, nuclear and mitochondrial splicing, and ribosome and spliceosome assembly. Based on their distribution patterns, some members of this family are believed to be involved in embryogenesis, spermatogenesis, and cellular growth and division. This gene encodes a DEAD box protein, which is an antigen recognized by autoimmune antibodies from a patient with watermelon stomach disease. This protein unwinds double-stranded RNA, folds single-stranded RNA, and may play important roles in ribosomal RNA biogenesis, RNA editing, RNA transport, and general transcription. [provided by RefSeq, Jul 2008]

Canonical amino-acid sequenceUniProt

783 residues, UniProt reviewed canonical sequence.

>Q9NR30|DDX21
     1  MPGKLRSDAG LESDTAMKKG ETLRKQTEEK EKKEKPKSDK TEEIAEEEET VFPKAKQVKK
    61  KAEPSEVDMN SPKSKKAKKK EEPSQNDISP KTKSLRKKKE PIEKKVVSSK TKKVTKNEEP
   121  SEEEIDAPKP KKMKKEKEMN GETREKSPKL KNGFPHPEPD CNPSEAASEE SNSEIEQEIP
   181  VEQKEGAFSN FPISEETIKL LKGRGVTFLF PIQAKTFHHV YSGKDLIAQA RTGTGKTFSF
   241  AIPLIEKLHG ELQDRKRGRA PQVLVLAPTR ELANQVSKDF SDITKKLSVA CFYGGTPYGG
   301  QFERMRNGID ILVGTPGRIK DHIQNGKLDL TKLKHVVLDE VDQMLDMGFA DQVEEILSVA
   361  YKKDSEDNPQ TLLFSATCPH WVFNVAKKYM KSTYEQVDLI GKKTQKTAIT VEHLAIKCHW
   421  TQRAAVIGDV IRVYSGHQGR TIIFCETKKE AQELSQNSAI KQDAQSLHGD IPQKQREITL
   481  KGFRNGSFGV LVATNVAARG LDIPEVDLVI QSSPPKDVES YIHRSGRTGR AGRTGVCICF
   541  YQHKEEYQLV QVEQKAGIKF KRIGVPSATE IIKASSKDAI RLLDSVPPTA ISHFKQSAEK
   601  LIEEKGAVEA LAAALAHISG ATSVDQRSLI NSNVGFVTMI LQCSIEMPNI SYAWKELKEQ
   661  LGEEIDSKVK GMVFLKGKLG VCFDVPTASV TEIQEKWHDS RRWQLSVATE QPELEGPREG
   721  YGGFRGQREG SRGFRGQRDG NRRFRGQREG SRGPRGQRSG GGNKSNRSQN KGQKRSFSKA
   781  FGQ

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against DDX21 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)
0.41
Highest tissue expression
92 nTPM

Expression across tissuesHPA

Tissue

  • bone marrow: 92 nTPM
  • urinary bladder: 75 nTPM
  • adipose tissue: 51 nTPM
  • appendix: 49 nTPM
  • tonsil: 47 nTPM
  • lymph node: 46 nTPM

Single-cell type

  • suprabasal keratinocytes: 576 nCPM
  • basal keratinocytes: 574 nCPM
  • esophageal basal cells: 392 nCPM
  • monocytes: 391 nCPM
  • erythrocyte progenitors: 365 nCPM
  • neutrophils: 357 nCPM

Immune cell

  • eosinophil: 20 nTPM
  • non-classical monocyte: 18 nTPM
  • intermediate monocyte: 15 nTPM
  • MAIT T-cell: 15 nTPM
  • memory B-cell: 13 nTPM
  • naive B-cell: 11 nTPM

Brain region

  • spinal cord: 16 nTPM
  • medulla oblongata: 16 nTPM
  • white matter: 16 nTPM
  • midbrain: 16 nTPM
  • hypothalamus: 15 nTPM
  • pons: 14 nTPM

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about DDX21.

Disease | ImmuneIEDB

Conditions an epitope on DDX21 was assayed in.

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)
0.18
gnomAD pLI
1
gnomAD missense Z
2.45
DepMap mean gene effect
-1.29
DepMap dependency class
common

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

Molecular functions

Cellular components

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of DDX21 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 DDX21 as an antibody target. Whether an autoantibody or antibody against DDX21 could matter depends on whether native DDX21 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

DDX21 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.

Source-annotated serology context

The source annotations explicitly mention antibody, autoantibody, autoantigen, or autoimmune context. This is biological context, not study-specific reactivity.

  • This gene encodes a DEAD box protein, which is an antigen recognized by autoimmune antibodies from a patient with watermelon stomach disease.

Canonical record: https://seroatlas.com/gene/DDX21. 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).

© 2026 · Seroatlas, Discover Oregon LLC · Terms of use

Loading the interactive Seroatlas protein explorer...