Seroatlas · Human Serome Atlas

TM4SF18

Transmembrane 4 L6 family member 18

Also known as: L6D, T4S18_HUMAN

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

Protein identityUniProt · HPA

UniProt accession: Q96CE8
Gene: TM4SF18
Ensembl: ENSG00000163762
Chromosome: 3
Canonical length: 201 aa
Protein class: Predicted membrane proteins, Transporters
Subcellular location: Plasma membrane

OverviewNCBI Gene

Predicted to be active in membrane. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

201 residues, UniProt reviewed canonical sequence.

>Q96CE8|TM4SF18
     1  MGSRKCGGCL SCLLIPLALW SIIVNILLYF PNGQTSYASS NKLTNYVWYF EGICFSGIMM
    61  LIVTTVLLVL ENNNNYKCCQ SENCSKKYVT LLSIIFSSLG IAFSGYCLVI SALGLVQGPY
   121  CRTLDGWEYA FEGTAGRFLT DSSIWIQCLE PAHVVEWNII LFSILITLSG LQVIICLIRV
   181  VMQLSKILCG SYSVIFQPGI I

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against TM4SF18 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: Unknown
Secreted: No
Transmembrane segments: 4
Mean surface accessibility (rSASA): 0.31
Highest tissue expression: 32 nTPM

Expression across tissuesHPA

Tissue

spleen: 32 nTPM
adipose tissue: 20 nTPM
kidney: 18 nTPM
placenta: 16 nTPM
breast: 15 nTPM
smooth muscle: 14 nTPM

Single-cell type

lymphatic endothelial cells: 187 nCPM
vascular endothelial cells: 153 nCPM
breast hormone-responsive cells: 73 nCPM
pancreatic duct cells: 36 nCPM
epididymal efferent duct absorptive cells: 27 nCPM
breast secretory cells: 24 nCPM

Immune cell

NK-cell: 0.4 nTPM
basophil: 0.3 nTPM
memory B-cell: 0.1 nTPM
naive B-cell: 0.1 nTPM
plasmacytoid DC: 0.1 nTPM
classical monocyte: 0 nTPM

Brain region

thalamus: 16 nTPM
medulla oblongata: 15 nTPM
pons: 14 nTPM
choroid plexus: 12 nTPM
hypothalamus: 12 nTPM
white matter: 12 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): 1.6
gnomAD pLI: 0
gnomAD missense Z: -0.13
DepMap mean gene effect: -0.08
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

Cellular components

membrane

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads TM4SF18 as an antibody target. Whether an autoantibody or antibody against TM4SF18 could matter depends on whether native TM4SF18 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

TM4SF18 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 TM4SF18 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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