Seroatlas · Human Serome Atlas

CTRB1

Chymotrypsinogen B

Also known as: CTRB, CTRB1_HUMAN

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

Protein identityUniProt · HPA

UniProt accession: P17538
Gene: CTRB1
Ensembl: ENSG00000168925
Chromosome: 16
Canonical length: 263 aa
Protein class: Enzymes, Predicted intracellular proteins, Predicted secreted proteins
Secretome location: Secreted to digestive system

OverviewNCBI Gene

This gene encodes a member of the serine protease family of enzymes and forms a principal precursor of the pancreatic proteolytic enzymes. The encoded preproprotein is synthesized in the acinar cells of the pancreas and secreted into the small intestine where it undergoes proteolytic activation to generate a functional enzyme. This CTRB1 gene is located head-to-head with the related CTRB2 gene. Some human populations have an alternate haplotype which inverts a 16.6 Kb region containing portions of intron 1, exon 1, and the upstream sequence of the CTRB1 and CTRB2 genes. In this inversion haplotype exon 1 and flanking sequence is swapped in CTRB1 and CTRB2. This inversion is associated with differential gene expression and increased risk for chronic pancreatitis. The GRCh38 assembly represents the minor allele for SNP rs8048956 of the CTRB1 gene. SNP rs8048956 in intron 1 of the CTRB2 gene is diagnostic for this inversion. This CTRB1 gene encodes distinct isoforms, some or all of which may undergo similar processing to generate the mature protein. [provided by RefSeq, Jan 2021]

Canonical amino-acid sequenceUniProt

263 residues, UniProt reviewed canonical sequence.

>P17538|CTRB1
     1  MASLWLLSCF SLVGAAFGCG VPAIHPVLSG LSRIVNGEDA VPGSWPWQVS LQDKTGFHFC
    61  GGSLISEDWV VTAAHCGVRT SDVVVAGEFD QGSDEENIQV LKIAKVFKNP KFSILTVNND
   121  ITLLKLATPA RFSQTVSAVC LPSADDDFPA GTLCATTGWG KTKYNANKTP DKLQQAALPL
   181  LSNAECKKSW GRRITDVMIC AGASGVSSCM GDSGGPLVCQ KDGAWTLVGI VSWGSDTCST
   241  SSPGVYARVT KLIPWVQKIL AAN

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against CTRB1 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): 0.27
Highest tissue expression: 126,233 nTPM

Expression across tissuesHPA

Tissue

pancreas: 126,233 nTPM
blood vessel: 24 nTPM
ovary: 23 nTPM
adipose tissue: 22 nTPM
salivary gland: 21 nTPM
heart muscle: 21 nTPM

Single-cell type

pancreatic acinar cells: 32,624 nCPM
pancreatic duct cells: 64 nCPM
oocytes: 37 nCPM
monocytes: 14 nCPM
epicardial cells: 6.8 nCPM
pancreatic islet cells: 4.7 nCPM

Immune cell

basophil: 0 nTPM
classical monocyte: 0 nTPM
eosinophil: 0 nTPM
gdT-cell: 0 nTPM
intermediate monocyte: 0 nTPM
MAIT T-cell: 0 nTPM

Brain region

cerebellum: 1.2 nTPM
basal ganglia: 0.7 nTPM
cerebral cortex: 0.7 nTPM
white matter: 0.7 nTPM
amygdala: 0.6 nTPM
pons: 0.5 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): 1.83
gnomAD pLI: 0
gnomAD missense Z: -0.53
DepMap mean gene effect: -0.1
DepMap dependency class: selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 1% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

Molecular functions

serine-type endopeptidase activity

Cellular components

extracellular region

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads CTRB1 as an antibody target. Whether an autoantibody or antibody against CTRB1 could matter depends on whether native CTRB1 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

CTRB1 is annotated as secreted, so native CTRB1 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 CTRB1 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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