# Epitope

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

## TL;DR

The exact small patch on an antigen that an antibody or T cell actually grips, like the specific spot on a door handle a hand grabs. Two antibodies can bind the same protein at different epitopes.

## Summary

An epitope is typically a cluster of five to fifteen amino acids on the surface of a protein. Trastuzumab and pertuzumab both bind HER2 but at different epitopes, which is why they can be given together, and zanidatamab is a single antibody built to grab both spots at once. For T cells, the epitope is a short peptide fragment held in an HLA molecule on the cell surface; a mutation that changes or removes the epitope lets a tumour cell slip past an antibody or T cell without changing anything else.

## Fields

- Kind: Term
- Last checked: 2026-09-09
- Also known as: epitopes; binding site; binding sites; binding domain; binding domains

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Epitope
- Wikipedia: https://en.wikipedia.org/wiki/Epitope

## Connected records

- terms: [Antibody](https://onco.cc/terms/antibody/), [Antigen](https://onco.cc/terms/antigen/), [Neoantigen](https://onco.cc/terms/neoantigen/), [T cell](https://onco.cc/terms/t-cell/)
- targets: [HER2](https://onco.cc/targets/her2/)
- drugs: [Trastuzumab](https://onco.cc/drugs/trastuzumab/), [Zanidatamab](https://onco.cc/drugs/zanidatamab/)

---
JSON: https://onco.cc/api/v1/entities/epitope.json