Seroatlas · Human Serome Atlas

HAPLN2

Hyaluronan and proteoglycan link protein 2

Also known as: BRAL1, HPLN2_HUMAN

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

Protein identityUniProt · HPA

UniProt accession: Q9GZV7
Gene: HAPLN2
Ensembl: ENSG00000132702
Chromosome: 1
Canonical length: 340 aa
Protein class: Predicted secreted proteins
Secretome location: Secreted in brain

OverviewNCBI Gene

Predicted to enable hyaluronic acid binding activity. Predicted to be involved in central nervous system development and skeletal system development. Predicted to act upstream of or within establishment of blood-nerve barrier and extracellular matrix assembly. Predicted to be located in extracellular matrix. Predicted to be active in extracellular space; perineuronal net; and synapse. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

340 residues, UniProt reviewed canonical sequence.

>Q9GZV7|HAPLN2
     1  MPGWLTLPTL CRFLLWAFTI FHKAQGDPAS HPGPHYLLPP IHEVIHSHRG ATATLPCVLG
    61  TTPPSYKVRW SKVEPGELRE TLILITNGLH ARGYGPLGGR ARMRRGHRLD ASLVIAGVRL
   121  EDEGRYRCEL INGIEDESVA LTLSLEGVVF PYQPSRGRYQ FNYYEAKQAC EEQDGRLATY
   181  SQLYQAWTEG LDWCNAGWLL EGSVRYPVLT ARAPCGGRGR PGIRSYGPRD RMRDRYDAFC
   241  FTSALAGQVF FVPGRLTLSE AHAACRRRGA VVAKVGHLYA AWKFSGLDQC DGGWLADGSV
   301  RFPITTPRPR CGGLPDPGVR SFGFPRPQQA AYGTYCYAEN

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against HAPLN2 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): 0.31
Highest tissue expression: 660 nTPM

Expression across tissuesHPA

Tissue

spinal cord: 660 nTPM
midbrain: 219 nTPM
hippocampal formation: 113 nTPM
basal ganglia: 79 nTPM
hypothalamus: 78 nTPM
amygdala: 60 nTPM

Single-cell type

oligodendrocytes: 333 nCPM
oligodendrocyte progenitor cells: 28 nCPM
pericytes: 24 nCPM
vascular smooth muscle cells: 22 nCPM
microglia: 10 nCPM
smooth muscle cells: 10 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

medulla oblongata: 549 nTPM
white matter: 503 nTPM
cerebellum: 355 nTPM
pons: 331 nTPM
midbrain: 290 nTPM
basal ganglia: 280 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): 1.29
gnomAD pLI: 0
gnomAD missense Z: 1.31
DepMap mean gene effect: -0.43
DepMap dependency class: selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 3% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

Molecular functions

hyaluronic acid binding

Cellular components

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads HAPLN2 as an antibody target. Whether an autoantibody or antibody against HAPLN2 could matter depends on whether native HAPLN2 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

HAPLN2 is annotated as secreted, so native HAPLN2 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 HAPLN2 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Loading the interactive Seroatlas protein explorer...