Seroatlas · Human Serome Atlas

SS18

Protein SSXT

Also known as: SMARCL1, SSXT, SSXT_HUMAN, SYT

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

Protein identityUniProt · HPA

UniProt accession: Q15532
Gene: SS18
Ensembl: ENSG00000141380
Chromosome: 18
Canonical length: 418 aa
Protein class: Cancer-related genes, Disease related genes, Predicted intracellular proteins
Subcellular location: Nucleoplasm,Cytosol

OverviewNCBI Gene

Enables transcription coactivator activity. Involved in positive regulation of transcription by RNA polymerase II. Part of SWI/SNF complex. Implicated in synovial sarcoma. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

418 residues, UniProt reviewed canonical sequence.

>Q15532|SS18
     1  MSVAFAAPRQ RGKGEITPAA IQKMLDDNNH LIQCIMDSQN KGKTSECSQY QQMLHTNLVY
    61  LATIADSNQN MQSLLPAPPT QNMPMGPGGM NQSGPPPPPR SHNMPSDGMV GGGPPAPHMQ
   121  NQMNGQMPGP NHMPMQGPGP NQLNMTNSSM NMPSSSHGSM GGYNHSVPSS QSMPVQNQMT
   181  MSQGQPMGNY GPRPNMSMQP NQGPMMHQQP PSQQYNMPQG GGQHYQGQQP PMGMMGQVNQ
   241  GNHMMGQRQI PPYRPPQQGP PQQYSGQEDY YGDQYSHGGQ GPPEGMNQQY YPDGHNDYGY
   301  QQPSYPEQGY DRPYEDSSQH YYEGGNSQYG QQQDAYQGPP PQQGYPPQQQ QYPGQQGYPG
   361  QQQGYGPSQG GPGPQYPNYP QGQGQQYGGY RPTQPGPPQP PQQRPYGYDQ GQYGNYQQ

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against SS18 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): 0.69
Highest tissue expression: 49 nTPM

Expression across tissuesHPA

Tissue

parathyroid gland: 49 nTPM
ovary: 46 nTPM
adrenal gland: 44 nTPM
thyroid gland: 42 nTPM
liver: 40 nTPM
skin: 39 nTPM

Single-cell type

sertoli cells: 369 nCPM
pituicytes/fscs: 165 nCPM
oligodendrocytes: 148 nCPM
choroid plexus epithelial cells: 143 nCPM
syncytiotrophoblasts: 138 nCPM
adipocytes: 135 nCPM

Immune cell

basophil: 27 nTPM
NK-cell: 25 nTPM
non-classical monocyte: 20 nTPM
intermediate monocyte: 20 nTPM
eosinophil: 19 nTPM
MAIT T-cell: 19 nTPM

Brain region

white matter: 44 nTPM
choroid plexus: 40 nTPM
medulla oblongata: 39 nTPM
midbrain: 37 nTPM
basal ganglia: 36 nTPM
hypothalamus: 35 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): 0.38
gnomAD pLI: 0.75
gnomAD missense Z: 1.06
DepMap mean gene effect: 0.13
DepMap dependency class: selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 6% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

Molecular functions

transcription coactivator activity

Cellular components

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of SS18 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 SS18 as an antibody target. Whether an autoantibody or antibody against SS18 could matter depends on whether native SS18 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

SS18 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 SS18 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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