Seroatlas · Human Serome Atlas

SDC1

Syndecan-1

Also known as: CD138, SDC, SDC1_HUMAN, SYND1, syndecan

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

Protein identityUniProt · HPA

UniProt accession
P18827
Gene
SDC1
Ensembl
ENSG00000115884
Chromosome
2
Canonical length
310 aa
Protein class
Cancer-related genes, CD markers, Metabolic proteins, Plasma proteins, Predicted intracellular proteins, Predicted membrane proteins, Predicted secreted proteins, Transporters
Subcellular location
Focal adhesion sites
Secretome location
Secreted to blood

OverviewNCBI Gene

The protein encoded by this gene is a transmembrane (type I) heparan sulfate proteoglycan and is a member of the syndecan proteoglycan family. The syndecans mediate cell binding, cell signaling, and cytoskeletal organization and syndecan receptors are required for internalization of the HIV-1 tat protein. The syndecan-1 protein functions as an integral membrane protein and participates in cell proliferation, cell migration and cell-matrix interactions via its receptor for extracellular matrix proteins. Altered syndecan-1 expression has been detected in several different tumor types. While several transcript variants may exist for this gene, the full-length natures of only two have been described to date. These two represent the major variants of this gene and encode the same protein. [provided by RefSeq, Jul 2008]

Canonical amino-acid sequenceUniProt

310 residues, UniProt reviewed canonical sequence.

>P18827|SDC1
     1  MRRAALWLWL CALALSLQPA LPQIVATNLP PEDQDGSGDD SDNFSGSGAG ALQDITLSQQ
    61  TPSTWKDTQL LTAIPTSPEP TGLEATAAST STLPAGEGPK EGEAVVLPEV EPGLTAREQE
   121  ATPRPRETTQ LPTTHLASTT TATTAQEPAT SHPHRDMQPG HHETSTPAGP SQADLHTPHT
   181  EDGGPSATER AAEDGASSQL PAAEGSGEQD FTFETSGENT AVVAVEPDRR NQSPVDQGAT
   241  GASQGLLDRK EVLGGVIAGG LVGLIFAVCL VGFMLYRMKK KDEGSYSLEE PKQANGGAYQ
   301  KPTKQEEFYA

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against SDC1 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)
0.69
Highest tissue expression
472 nTPM

Expression across tissuesHPA

Tissue

  • liver: 472 nTPM
  • esophagus: 467 nTPM
  • skin: 423 nTPM
  • vagina: 234 nTPM
  • cervix: 161 nTPM
  • urinary bladder: 103 nTPM

Single-cell type

  • esophageal apical cells: 1,999 nCPM
  • esophageal suprabasal cells: 1,147 nCPM
  • ocular epithelial cells: 870 nCPM
  • hepatocytes: 682 nCPM
  • urothelial cells: 638 nCPM
  • prostatic hillock cells: 484 nCPM

Immune cell

  • memory B-cell: 0.9 nTPM
  • total PBMC: 0.1 nTPM
  • basophil: 0 nTPM
  • classical monocyte: 0 nTPM
  • eosinophil: 0 nTPM
  • gdT-cell: 0 nTPM

Brain region

  • midbrain: 37 nTPM
  • thalamus: 6.3 nTPM
  • cerebellum: 5.7 nTPM
  • hypothalamus: 5.3 nTPM
  • choroid plexus: 2.6 nTPM
  • pons: 2.6 nTPM

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about SDC1.

Disease | ImmuneIEDB

Conditions an epitope on SDC1 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)
0.96
gnomAD pLI
0.01
gnomAD missense Z
-0.04
DepMap mean gene effect
-0.09
DepMap dependency class
selective

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 SDC1 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 SDC1 as an antibody target. Whether an autoantibody or antibody against SDC1 could matter depends on whether native SDC1 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

SDC1 is annotated as secreted, so native SDC1 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 SDC1 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/SDC1. 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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