Seroatlas · Human Serome Atlas

ERP44

Endoplasmic reticulum resident protein 44

Also known as: ERP44_HUMAN, KIAA0573, PDIA10, TXNDC4

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

Protein identityUniProt · HPA

UniProt accession: Q9BS26
Gene: ERP44
Ensembl: ENSG00000023318
Chromosome: 9
Canonical length: 406 aa
Protein class: Plasma proteins, Predicted intracellular proteins
Secretome location: Intracellular and membrane

OverviewNCBI Gene

This gene encodes a member of the protein disulfide isomerase (PDI) family of endoplasmic reticulum (ER) proteins. It has an inferred N-terminal signal peptide, a catalytically active thioredoxin (TRX) domain, two TRX-like domains and a C-terminal ER-retention sequence. This protein functions as a pH-regulated chaperone of the secretory pathway and likely plays a role in protein quality control at the endoplasmic reticulum - Golgi interface. [provided by RefSeq, Dec 2016]

Canonical amino-acid sequenceUniProt

406 residues, UniProt reviewed canonical sequence.

>Q9BS26|ERP44
     1  MHPAVFLSLP DLRCSLLLLV TWVFTPVTTE ITSLDTENID EILNNADVAL VNFYADWCRF
    61  SQMLHPIFEE ASDVIKEEFP NENQVVFARV DCDQHSDIAQ RYRISKYPTL KLFRNGMMMK
   121  REYRGQRSVK ALADYIRQQK SDPIQEIRDL AEITTLDRSK RNIIGYFEQK DSDNYRVFER
   181  VANILHDDCA FLSAFGDVSK PERYSGDNII YKPPGHSAPD MVYLGAMTNF DVTYNWIQDK
   241  CVPLVREITF ENGEELTEEG LPFLILFHMK EDTESLEIFQ NEVARQLISE KGTINFLHAD
   301  CDKFRHPLLH IQKTPADCPV IAIDSFRHMY VFGDFKDVLI PGKLKQFVFD LHSGKLHREF
   361  HHGPDPTDTA PGEQAQDVAS SPPESSFQKL APSEYRYTLL RDRDEL

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against ERP44 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): 0.3
Highest tissue expression: 27 nTPM

Expression across tissuesHPA

Tissue

liver: 27 nTPM
epididymis: 27 nTPM
placenta: 26 nTPM
pancreas: 23 nTPM
thyroid gland: 22 nTPM
stomach: 19 nTPM

Single-cell type

esophageal apical cells: 378 nCPM
syncytiotrophoblasts: 308 nCPM
epididymal principal cells: 255 nCPM
extravillous trophoblasts: 220 nCPM
decidual stromal cells: 197 nCPM
plasma cells: 195 nCPM

Immune cell

non-classical monocyte: 43 nTPM
intermediate monocyte: 33 nTPM
classical monocyte: 32 nTPM
neutrophil: 32 nTPM
eosinophil: 30 nTPM
total PBMC: 28 nTPM

Brain region

cerebellum: 20 nTPM
choroid plexus: 13 nTPM
hypothalamus: 13 nTPM
midbrain: 12 nTPM
cerebral cortex: 12 nTPM
basal ganglia: 11 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): 0.27
gnomAD pLI: 0.99
gnomAD missense Z: 2.29
DepMap mean gene effect: -0.04
DepMap dependency class: selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 6% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

Molecular functions

protein disulfide isomerase activity

Cellular components

Protein domainsUniProt · Pfam · InterPro

Thioredoxin domain
Thioredoxin-like superfamily
Thioredoxin
Thioredoxin-like domain
Endoplasmic reticulum resident protein 44, second TRX-like domain b
Endoplasmic reticulum resident protein 44, first TRX-like domain b
Endoplasmic reticulum resident protein 44

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of ERP44 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 ERP44 as an antibody target. Whether an autoantibody or antibody against ERP44 could matter depends on whether native ERP44 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

ERP44 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 ERP44 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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