CST4

Protein identityUniProt · HPA

UniProt accession

P01036

Gene

CST4

Ensembl

ENSG00000101441

Chromosome

20

Canonical length

141 aa

Protein class

Predicted secreted proteins

Secretome location

Secreted to digestive system

OverviewNCBI Gene

The cystatin superfamily encompasses proteins that contain multiple cystatin-like sequences. Some of the members are active cysteine protease inhibitors, while others have lost or perhaps never acquired this inhibitory activity. There are three inhibitory families in the superfamily, including the type 1 cystatins (stefins), type 2 cystatins and the kininogens. The type 2 cystatin proteins are a class of cysteine proteinase inhibitors found in a variety of human fluids and secretions. The cystatin locus on chromosome 20 contains the majority of the type 2 cystatin genes and pseudogenes. This gene is located in the cystatin locus and encodes a type 2 salivary cysteine peptidase inhibitor. The protein is an S-type cystatin, based on its high level of expression in saliva, tears and seminal plasma. The specific role in these fluids is unclear but antibacterial and antiviral activity is present, consistent with a protective function. [provided by RefSeq, Jul 2008]

Canonical amino-acid sequenceUniProt

141 residues, UniProt reviewed canonical sequence.

>P01036|CST4
     1  MARPLCTLLL LMATLAGALA SSSKEENRII PGGIYDADLN DEWVQRALHF AISEYNKATE
    61  DEYYRRPLQV LRAREQTFGG VNYFFDVEVG RTICTKSQPN LDTCAFHEQP ELQKKQLCSF
   121  EIYEVPWEDR MSLVNSRCQE A

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against CST4 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)

0.39

Highest tissue expression

27,277 nTPM

Expression across tissuesHPA

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)

1.93

gnomAD pLI

0

gnomAD missense Z

-2.07

DepMap mean gene effect

-0.12

DepMap dependency class

selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 2% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

• detection of chemical stimulus involved in sensory perception of bitter taste
• negative regulation of proteolysis

Molecular functions

• cysteine-type endopeptidase inhibitor activity

Cellular components

• cytoplasm
• extracellular exosome
• extracellular space
• vesicle

Protein domainsUniProt · Pfam · InterPro

• Cystatin domain
• Proteinase inhibitor I25, cystatin, conserved site
• Cystatin superfamily
• Cystatin domain

KeywordsUniProt

• Disulfide bond
• Phosphoprotein
• Protease inhibitor
• Secreted
• Signal
• Thiol protease inhibitor

InteractionsUniProt · HPA

Protein binding partners of CST4 in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.

• CST1