Seroatlas · Human Serome Atlas

PLAC1

Placenta-specific protein 1

Also known as: CT92, OOSP2B, OOSP2L, PLAC1_HUMAN

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

Protein identityUniProt · HPA

UniProt accession: Q9HBJ0
Gene: PLAC1
Ensembl: ENSG00000170965
Chromosome: X
Canonical length: 212 aa
Protein class: Predicted secreted proteins
Subcellular location: Vesicles,Cytosol
Secretome location: Secreted in female reproductive system

OverviewNCBI Gene

Involved in placenta development. Predicted to be located in extracellular region. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

212 residues, UniProt reviewed canonical sequence.

>Q9HBJ0|PLAC1
     1  MKVFKFIGLM ILLTSAFSAG SGQSPMTVLC SIDWFMVTVH PFMLNNDVCV HFHELHLGLG
    61  CPPNHVQPHA YQFTYRVTEC GIRAKAVSQD MVIYSTEIHY SSKGTPSKFV IPVSCAAPQK
   121  SPWLTKPCSM RVASKSRATA QKDEKCYEVF SLSQSSQRPN CDCPPCVFSE EEHTQVPCHQ
   181  AGAQEAQPLQ PSHFLDISED WSLHTDDMIG SM

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against PLAC1 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: 0
Mean surface accessibility (rSASA): 0.51
Highest tissue expression: 26 nTPM

Expression across tissuesHPA

Tissue

placenta: 26 nTPM
testis: 0.9 nTPM
ovary: 0.3 nTPM
fallopian tube: 0.2 nTPM
skin: 0.2 nTPM
breast: 0.1 nTPM

Single-cell type

fibroblasts: 25 nCPM
early primary spermatocytes: 23 nCPM
syncytiotrophoblasts: 18 nCPM
differentiating spermatogonia: 13 nCPM
peritubular myoid cells: 13 nCPM
adrenal medulla cells: 11 nCPM

Immune cell

basophil: 0 nTPM
classical monocyte: 0 nTPM
eosinophil: 0 nTPM
gdT-cell: 0 nTPM
intermediate monocyte: 0 nTPM
MAIT T-cell: 0 nTPM

Brain region

choroid plexus: 0.3 nTPM
cerebral cortex: 0.2 nTPM
amygdala: 0.1 nTPM
basal ganglia: 0.1 nTPM
cerebellum: 0.1 nTPM
hippocampal formation: 0.1 nTPM

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about PLAC1.

Disease | ImmuneIEDB

Conditions an epitope on PLAC1 was assayed in.

colorectal carcinoma T cell
head and neck squamous cell carcinoma T cell

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 missense Z: 0.26
DepMap mean gene effect: 0.01
DepMap dependency class: none

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

placenta development

Cellular components

extracellular region

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads PLAC1 as an antibody target. Whether an autoantibody or antibody against PLAC1 could matter depends on whether native PLAC1 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

PLAC1 is annotated as secreted, so native PLAC1 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 PLAC1 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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