# FKBP12 (FKBP1A)

Source: https://onco.cc/targets/fkbp12/  
OnCo record `fkbp12` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

FKBP12 is the small protein that rapamycin-type drugs grab first; the drug-FKBP12 pair then clamps onto mTOR and switches off its growth signalling.

## Summary

FK506-binding protein 1A (FKBP12) is a peptidyl-prolyl isomerase that acts as the intracellular receptor for rapamycin and its analogues. Everolimus and temsirolimus bind FKBP12, and the complex binds the FRB domain of mTOR, inhibiting mTORC1. The target is therefore listed for every rapalogue approved in kidney cancer, breast cancer, neuroendocrine tumours and tuberous sclerosis.

## Fields

- Kind: Target
- Last checked: 2026-09-04
- Symbol: FKBP1A
- Class: other
- Biology: An abundant cytosolic immunophilin that also regulates ryanodine and TGF-beta receptors; drug binding, not its own enzyme activity, is what matters for the mTOR effect.
- Where found: Ubiquitous, cytosolic; Required for the action of everolimus, temsirolimus and sirolimus

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/FKBP1A
- UniProt P62942: FKBP1A: https://www.uniprot.org/uniprotkb/P62942/entry
- HGNC:3711 FKBP1A: https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:3711
- ChEMBL target CHEMBL1902: https://www.ebi.ac.uk/chembl/explore/target/CHEMBL1902

## Connected records

- targets: [mTOR](https://onco.cc/targets/mtor/)
- cancers: [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/), [Renal cell carcinoma](https://onco.cc/cancers/rcc/)
- drugs: [Everolimus](https://onco.cc/drugs/everolimus/), [Temsirolimus](https://onco.cc/drugs/temsirolimus/)

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JSON: https://onco.cc/api/v1/entities/fkbp12.json