Cystatin-11

experimental

Also known as: CST11, Q9H112

Cystatin-11 (CST11, Q9H112) is a member of the type 2 cystatin family, characterized by its cysteine protease inhibitory activity. Its mechanism of action includes direct antibacterial activity against the Gram-negative bacterium *Escherichia coli*, likely mediated through interactions with bacterial cell membranes or inhibition of bacterial cysteine proteases, though the precise molecular target remains under investigation. Current research on Cystatin-11 is limited, with only four PubMed references available, indicating an experimental stage of study. Preliminary findings suggest its antimicrobial properties may be relevant to host defense, particularly in epithelial tissues where cystatins are often expressed. No in vivo or clinical data have been reported to date. Given the sparse evidence, clinical relevance is not yet established. Further studies are needed to elucidate its antimicrobial spectrum, mechanism, and potential therapeutic applications. For research purposes only — not medical advice.

Key data

Category
Immune Modulation
Sequence
MMAEPWQALQLLLAILLTLMALPYQARKKTFLSVHEVMAVENYAKDSLQWITDQYNKESDDKYHFRIFRVLKVQRQVTDHLEYHLNVEMQWTTCQKPETTNCVPQERELHKQVNCFFSVFAVPWFEQYKILNKSCSSD
Molecular weight
16506 g/mol
Research status
experimental
References
4
Tags
uniprot, alternative-splicing, antibiotic, antimicrobial, disulfide-bond, glycoprotein, protease-inhibitor, proteomics-identification, reference-proteome, secreted, signal, thiol-protease-inhibitor

Mechanism of action

Has antibacterial activity against the Gram-negative bacteria E.coli. May play a role in sperm maturation and fertilization

Research & studies

Proteomic Characterization of Bottlenose Dolphin (Tursiops truncatus) Urine
Journal of proteome research · 2026 · PubMed

1872 protein families identified across all dolphin urine samples (FDR < 0.01).; Cystatin 11 abundant in males (median 8.1%) but absent in females (median 0.0%).; Antimicrobial proteins cathelicidin and lysozyme comprised 2.66% of the urine proteome.; 27 human acute kidney injury markers and 12 putative stone formation proteins detected.

Expression and purification of soluble porcine cystatin 11 in Pichia pastoris
Applied biochemistry and biotechnology · 2014 · PubMed
Antimicrobial activity and molecular mechanism of the CRES protein
PloS one · 2012 · PubMed

CRES protein shows dose- and time-dependent antibacterial activity against E. coli and inhibits Ureaplasma urealyticum growth.; Antimicrobial activity is independent of disulfide bonds, as cysteine mutations did not impair effects.; The active antimicrobial region is located between amino acid residues 31 and 60 of the N-terminus.; CRES increases E. coli membrane permeabilization and inhibits macromolecular synthesis.

Cystatin 11: a new member of the cystatin type 2 family
Endocrinology · 2002 · PubMed

CST11 mRNA is expressed exclusively in the epididymis and is androgen regulated.; The CST11 gene has a three-exon structure similar to other cystatin family 2 genes, with an alternative transcript lacking exon 2.; CST11 protein is detected throughout the epididymis and on ejaculated human sperm.; Both intact and exon 2-deleted CST11 recombinant proteins exhibit antimicrobial activity against Escherichia coli.

Frequently asked questions

What is Cystatin-11?

Cystatin-11 (CST11, Q9H112) is a member of the type 2 cystatin family, characterized by its cysteine protease inhibitory activity. Its mechanism of action includes direct antibacterial activity against the Gram-negative bacterium *Escherichia coli*, likely mediated through interactions with bacterial cell membranes or

How does Cystatin-11 work?

Has antibacterial activity against the Gram-negative bacteria E.coli. May play a role in sperm maturation and fertilization

What is the research status of Cystatin-11?

Cystatin-11 is currently classified as experimental, with 4 research references on record. This is for research purposes only and is not medical advice.

What is the molecular weight of Cystatin-11?

Cystatin-11 has a molecular weight of approximately 16506 g/mol.

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