Seroatlas · Human Serome Atlas

ISM1

Isthmin-1

Also known as: bA149I18.1, C20orf82, ISM1_HUMAN

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

Protein identityUniProt · HPA

UniProt accession: B1AKI9
Gene: ISM1
Ensembl: ENSG00000101230
Chromosome: 20
Canonical length: 464 aa
Protein class: Predicted secreted proteins
Secretome location: Secreted in other tissues

OverviewNCBI Gene

Predicted to be involved in negative regulation of angiogenesis. Predicted to be located in extracellular region. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

464 residues, UniProt reviewed canonical sequence.

>B1AKI9|ISM1
     1  MVRLAAELLL LLGLLLLTLH ITVLRGSGAA DGPDAAAGNA SQAQLQNNLN VGSDTTSETS
    61  FSLSKEAPRE HLDHQAAHQP FPRPRFRQET GHPSLQRDFP RSFLLDLPNF PDLSKADING
   121  QNPNIQVTIE VVDGPDSEAD KDQHPENKPS WSVPSPDWRA WWQRSLSLAR ANSGDQDYKY
   181  DSTSDDSNFL NPPRGWDHTA PGHRTFETKD QPEYDSTDGE GDWSLWSVCS VTCGNGNQKR
   241  TRSCGYACTA TESRTCDRPN CPGIEDTFRT AATEVSLLAG SEEFNATKLF EVDTDSCERW
   301  MSCKSEFLKK YMHKVMNDLP SCPCSYPTEV AYSTADIFDR IKRKDFRWKD ASGPKEKLEI
   361  YKPTARYCIR SMLSLESTTL AAQHCCYGDN MQLITRGKGA GTPNLISTEF SAELHYKVDV
   421  LPWIICKGDW SRYNEARPPN NGQKCTESPS DEDYIKQFQE AREY

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against ISM1 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: Secreted
Secreted: Yes
Transmembrane segments: 0
Mean surface accessibility (rSASA): 0.48
Highest tissue expression: 35 nTPM

Expression across tissuesHPA

Tissue

thyroid gland: 35 nTPM
blood vessel: 23 nTPM
skin: 14 nTPM
placenta: 14 nTPM
breast: 13 nTPM
salivary gland: 12 nTPM

Single-cell type

breast myoepithelial cells: 160 nCPM
fibroblasts: 93 nCPM
fibro-adipogenic progenitors: 75 nCPM
pituitary stem cells: 55 nCPM
salivary myoepithelial cells: 44 nCPM
epicardial cells: 43 nCPM

Immune cell

memory CD4 T-cell: 1.1 nTPM
naive CD4 T-cell: 0.9 nTPM
total PBMC: 0.3 nTPM
memory CD8 T-cell: 0.1 nTPM
naive CD8 T-cell: 0.1 nTPM
basophil: 0 nTPM

Brain region

thalamus: 7.9 nTPM
hypothalamus: 7.8 nTPM
cerebral cortex: 3.9 nTPM
midbrain: 3.2 nTPM
pons: 3.1 nTPM
medulla oblongata: 3 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): 0.7
gnomAD pLI: 0.01
gnomAD missense Z: 1.07
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

negative regulation of angiogenesis

Cellular components

extracellular region

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads ISM1 as an antibody target. Whether an autoantibody or antibody against ISM1 could matter depends on whether native ISM1 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

ISM1 is annotated as secreted, so native ISM1 circulates and is directly accessible to antibodies. Secreted and cell-surface proteins are the autoantibody targets most likely to act like drugs, blocking or depleting the native protein.

Annotation status

The present source text does not explicitly label ISM1 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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