Seroatlas · Human Serome Atlas

IQSEC3

IQ motif and SEC7 domain-containing protein 3

Also known as: IQEC3_HUMAN, KIAA1110, MGC30156

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

Protein identityUniProt · HPA

UniProt accession: Q9UPP2
Gene: IQSEC3
Ensembl: ENSG00000120645
Chromosome: 12
Canonical length: 1182 aa
Protein class: Predicted intracellular proteins
Subcellular location: Nucleoplasm,Cytosol

OverviewNCBI Gene

Predicted to enable guanyl-nucleotide exchange factor activity. Predicted to be involved in several processes, including activation of GTPase activity; postsynapse organization; and regulation of small GTPase mediated signal transduction. Located in cytosol and nucleoplasm. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

1182 residues, UniProt reviewed canonical sequence.

>Q9UPP2|IQSEC3
     1  MESLLENPVR AVLYLKELTA IVQNQQSLIH TQRERIDELE RRLDELSAEN RSLWEHQQLL
    61  QAQPPPGLVP PSSAPLPAAP ATAPAAAARA QEPLQDQGQR SAAAPHPAPD RPPRQHHGQL
   121  LEQPQRGPGS RAHTPQSPHK HLGTQGAVTD KEKERPPSCC AAAGALLQHK SPSALGKGVL
   181  SRRPENETVL HQFCCPAADA CSDLASQSDG SCTQAGGGME DSVVAAAAVA AGRPSAHAPK
   241  AQAQELQEEE ERPGAGAASP RAGPQHKASP GRQQPALATA LCPHAPAASD YELSLDLKNK
   301  QIEMLEHKYG GHLVSRRAAC TIQTAFRQYQ LSKNFEKIRN SLLESRLPRR ISLRKVRSPT
   361  AESLAAEKAL MEGYGLVGLP LVRSPSLPPT FAGTLTELED SFTEQVQSLA KSIDDALSTW
   421  SLKTMCSLRE SGAYQLHQAL QAAAGPPGLE AEGRAPESAG PGPGDDAAET PGLPPAHSGT
   481  LMMAFRDVTV QIANQNISVS SSTALSVANC LGAQTVQAPA EPAAGKAEQG ETSGREAPEA
   541  PAVGREDASA EDSCAEAAAS GAADGATAPK TEEEEEEEET AEVGRGAEAE AGDLEQLSSS
   601  STSTKSAKSG SEASASASKD ALQAMILSLP RYHCENPASC KSPTLSTDTL RKRLYRIGLN
   661  LFNINPDKGI QFLISRGFIP DTPIGVAHFL LQRKGLSRQM IGEFLGNSKK QFNRDVLDCV
   721  VDEMDFSSME LDEALRKFQA HIRVQGEAQK VERLIEAFSQ RYCMCNPEVV QQFHNPDTIF
   781  ILAFAIILLN TDMYSPNIKP DRKMMLEDFI RNLRGVDDGA DIPRELVVGI YERIQQKELK
   841  SNEDHVTYVT KVEKSIVGMK TVLSVPHRRL VCCSRLFEVT DVNKLQKQAA HQREVFLFND
   901  LLVILKLCPK KKSSSTYTFC KSVGLLGMQF QLFENEYYSH GITLVTPLSG SEKKQVLHFC
   961  ALGSDEMQKF VEDLKESIAE VTELEQIRIE WELEKQQGTK TLSFKPCGAQ GDPQSKQGSP
  1021  TAKREAALRE RPAESTVEVS IHNRLQTSQH NSGLGAERGA PVPPPDLQPS PPRQQTPPLP
  1081  PPPPTPPGTL VQCQQIVKVI VLDKPCLARM EPLLSQALSC YTSSSSDSCG STPLGGPGSP
  1141  VKVTHQPPLP PPPPPYNHPH QFCPPGSLLH GHRYSSGSRS LV

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against IQSEC3 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): 0.5
Highest tissue expression: 61 nTPM

Expression across tissuesHPA

Tissue

cerebellum: 61 nTPM
cerebral cortex: 35 nTPM
hippocampal formation: 22 nTPM
amygdala: 20 nTPM
hypothalamus: 18 nTPM
basal ganglia: 13 nTPM

Single-cell type

other brain neurons: 120 nCPM
brain excitatory neurons: 109 nCPM
retinal amacrine cells: 87 nCPM
brain inhibitory neurons: 83 nCPM
early primary spermatocytes: 66 nCPM
retinal horizontal cells: 48 nCPM

Immune cell

plasmacytoid DC: 0.3 nTPM
naive CD8 T-cell: 0.2 nTPM
basophil: 0 nTPM
classical monocyte: 0 nTPM
eosinophil: 0 nTPM
gdT-cell: 0 nTPM

Brain region

cerebral cortex: 135 nTPM
cerebellum: 85 nTPM
white matter: 84 nTPM
hippocampal formation: 72 nTPM
thalamus: 66 nTPM
amygdala: 59 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): 0.47
gnomAD pLI: 0
gnomAD missense Z: 1.15
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

Molecular functions

guanyl-nucleotide exchange factor activity

Cellular components

cytosol
GABA-ergic synapse
glycinergic synapse
inhibitory synapse
nucleoplasm
postsynaptic density
postsynaptic membrane
postsynaptic specialization of symmetric synapse

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of IQSEC3 in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads IQSEC3 as an antibody target. Whether an autoantibody or antibody against IQSEC3 could matter depends on whether native IQSEC3 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

IQSEC3 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 IQSEC3 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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