Seroatlas · Human Serome Atlas

ARHGAP18

Rho GTPase-activating protein 18

Also known as: bA307O14.2, MacGAP, RHG18_HUMAN

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

Protein identityUniProt · HPA

UniProt accession: Q8N392
Gene: ARHGAP18
Ensembl: ENSG00000146376
Chromosome: 6
Canonical length: 663 aa
Protein class: Predicted intracellular proteins
Subcellular location: Nuclear speckles,Plasma membrane,Cytosol

OverviewNCBI Gene

Enables GTPase activator activity. Involved in several processes, including regulation of actin filament polymerization; regulation of small GTPase mediated signal transduction; and small GTPase-mediated signal transduction. Located in cytosol; nuclear speck; and plasma membrane. Part of cytoplasmic microtubule and ruffle. Implicated in schizophrenia. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

663 residues, UniProt reviewed canonical sequence.

>Q8N392|ARHGAP18
     1  MSWLSSSQGV VLTAYHPSGK DQTVGNSHAK AGEEATSSRR YGQYTMNQES TTIKVMEKPP
    61  FDRSISQDSL DELSMEDYWI ELENIKKSSE NSQEDQEVVV VKEPDEGELE EEWLKEAGLS
   121  NLFGESAGDP QESIVFLSTL TRTQAAAVQK RVETVSQTLR KKNKQYQIPD VRDIFAQQRE
   181  SKETAPGGTE SQSLRTNENK YQGRDDEASN LVGEEKLIPP EETPAPETDI NLEVSFAEQA
   241  LNQKESSKEK IQKSKGDDAT LPSFRLPKDK TGTTRIGDLA PQDMKKVCHL ALIELTALYD
   301  VLGIELKQQK AVKIKTKDSG LFCVPLTALL EQDQRKVPGM RIPLIFQKLI SRIEERGLET
   361  EGLLRIPGAA IRIKNLCQEL EAKFYEGTFN WESVKQHDAA SLLKLFIREL PQPLLSVEYL
   421  KAFQAVQNLP TKKQQLQALN LLVILLPDAN RDTLKALLEF LQRVIDNKEK NKMTVMNVAM
   481  VMAPNLFMCH ALGLKSSEQR EFVMAAGTAN TMHLLIKYQK LLWTIPKFIV NQVRKQNTEN
   541  HKKDKRAMKK LLKKMAYDRE KYEKQDKSTN DADVPQGVIR VQAPHLSKVS MAIQLTEELK
   601  ASDVLARFLS QESGVAQTLK KGEVFLYEIG GNIGERCLDD DTYMKDLYQL NPNAEWVIKS
   661  KPL

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against ARHGAP18 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: Intracellular
Secreted: No
Transmembrane segments: 0
Mean surface accessibility (rSASA): 0.37
Highest tissue expression: 35 nTPM

Expression across tissuesHPA

Tissue

adrenal gland: 35 nTPM
pancreas: 31 nTPM
lung: 27 nTPM
fallopian tube: 27 nTPM
kidney: 27 nTPM
stomach: 26 nTPM

Single-cell type

platelets: 1,276 nCPM
renal collecting duct intercalated cells: 1,216 nCPM
mast cells: 944 nCPM
breast lactating cells: 799 nCPM
respiratory ionocytes: 770 nCPM
respiratory ciliated cells: 547 nCPM

Immune cell

eosinophil: 14 nTPM
basophil: 12 nTPM
plasmacytoid DC: 12 nTPM
total PBMC: 6 nTPM
intermediate monocyte: 5.8 nTPM
memory CD8 T-cell: 5.5 nTPM

Brain region

choroid plexus: 33 nTPM
thalamus: 15 nTPM
midbrain: 13 nTPM
medulla oblongata: 11 nTPM
hypothalamus: 9.3 nTPM
white matter: 8.6 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): 0.86
gnomAD pLI: 0
gnomAD missense Z: 0.72
DepMap mean gene effect: 0.1
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

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of ARHGAP18 in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.

MPHOSPH6

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads ARHGAP18 as an antibody target. Whether an autoantibody or antibody against ARHGAP18 could matter depends on whether native ARHGAP18 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

ARHGAP18 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 ARHGAP18 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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