Seroatlas · Human Serome Atlas

APLN

Apelin

Also known as: APEL_HUMAN, apelin, XNPEP2

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

Protein identityUniProt · HPA

UniProt accession: Q9ULZ1
Gene: APLN
Ensembl: ENSG00000171388
Chromosome: X
Canonical length: 77 aa
Protein class: Predicted secreted proteins
Secretome location: Secreted in other tissues

OverviewNCBI Gene

This gene encodes a peptide that functions as an endogenous ligand for the G-protein coupled apelin receptor. The encoded preproprotein is proteolytically processed into biologically active C-terminal peptide fragments. These peptide fragments activate different tissue specific signaling pathways that regulate diverse biological functions including fluid homeostasis, cardiovascular function and insulin secretion. This protein also functions as a coreceptor for the human immunodeficiency virus 1. [provided by RefSeq, Feb 2016]

Canonical amino-acid sequenceUniProt

77 residues, UniProt reviewed canonical sequence.

>Q9ULZ1|APLN
     1  MNLRLCVQAL LLLWLSLTAV CGGSLMPLPD GNGLEDGNVR HLVQPRGSRN GPGPWQGGRR
    61  KFRRQRPRLS HKGPMPF

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against APLN 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): 0.69
Highest tissue expression: 51 nTPM

Expression across tissuesHPA

Tissue

placenta: 51 nTPM
spinal cord: 29 nTPM
midbrain: 25 nTPM
hypothalamus: 17 nTPM
amygdala: 16 nTPM
cerebral cortex: 15 nTPM

Single-cell type

adrenal medulla cells: 21 nCPM
pituitary stem cells: 20 nCPM
podocytes: 18 nCPM
breast myoepithelial cells: 12 nCPM
somatotrophs: 10 nCPM
astrocytes: 7.7 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

white matter: 63 nTPM
thalamus: 61 nTPM
medulla oblongata: 55 nTPM
spinal cord: 52 nTPM
midbrain: 44 nTPM
pons: 42 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): 1.52
gnomAD pLI: 0.46
gnomAD missense Z: -0.24
DepMap mean gene effect: 0
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

Molecular functions

Cellular components

Protein domainsUniProt · Pfam · InterPro

Apelin
APJ endogenous ligand

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of APLN in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.

MDFI

Antibody and autoantibody relevanceSeroatlas analysis

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

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

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