Seroatlas · Human Serome Atlas

CYB561A3

Lysosomal membrane ascorbate-dependent ferrireductase CYB561A3

Also known as: CYAC3_HUMAN, CYBASC3

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

Protein identityUniProt · HPA

UniProt accession: Q8NBI2
Gene: CYB561A3
Ensembl: ENSG00000162144
Chromosome: 11
Canonical length: 242 aa
Protein class: Enzymes, Predicted intracellular proteins, Predicted membrane proteins
Subcellular location: Nucleoli,Vesicles
Quaternary structure: Homodimer

OverviewNCBI Gene

Predicted to enable transmembrane ascorbate ferrireductase activity. Predicted to be involved in intracellular iron ion homeostasis. Located in nucleolus. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

242 residues, UniProt reviewed canonical sequence.

>Q8NBI2|CYB561A3
     1  MVSGRFYLSC LLLGSLGSMC ILFTIYWMQY WRGGFAWNGS IYMFNWHPVL MVAGMVVFYG
    61  GASLVYRLPQ SWVGPKLPWK LLHAALHLMA FVLTVVGLVA VFTFHNHGRT ANLYSLHSWL
   121  GITTVFLFAC QWFLGFAVFL LPWASMWLRS LLKPIHVFFG AAILSLSIAS VISGINEKLF
   181  FSLKNTTRPY HSLPSEAVFA NSTGMLVVAF GLLVLYILLA SSWKRPEPGI LTDRQPLLHD
   241  GE

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against CYB561A3 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: Other membrane
Secreted: No
Transmembrane segments: 6
Mean surface accessibility (rSASA): 0.3
Highest tissue expression: 292 nTPM

Expression across tissuesHPA

Tissue

adrenal gland: 292 nTPM
skin: 72 nTPM
tonsil: 66 nTPM
lymph node: 66 nTPM
spleen: 47 nTPM
liver: 32 nTPM

Single-cell type

melanocytes: 530 nCPM
pdcs: 295 nCPM
adrenal cortex cells: 166 nCPM
early spermatids: 73 nCPM
cytotrophoblasts: 61 nCPM
b-cells: 59 nCPM

Immune cell

plasmacytoid DC: 844 nTPM
naive B-cell: 388 nTPM
memory B-cell: 315 nTPM
total PBMC: 85 nTPM
classical monocyte: 66 nTPM
non-classical monocyte: 64 nTPM

Brain region

choroid plexus: 38 nTPM
midbrain: 30 nTPM
white matter: 29 nTPM
medulla oblongata: 28 nTPM
pons: 27 nTPM
spinal cord: 27 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): 0.9
gnomAD pLI: 0.01
gnomAD missense Z: 0.9
DepMap mean gene effect: -0.01
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

intracellular iron ion homeostasis

Molecular functions

Cellular components

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads CYB561A3 as an antibody target. Whether an autoantibody or antibody against CYB561A3 could matter depends on whether native CYB561A3 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

CYB561A3 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 CYB561A3 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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