---
title: "Receptor Tyrosine Kinases and Phosphorylation Cascades"
description: "Growth factor receptors pair up when a ligand binds, then phosphorylate each other on tyrosine residues. Those phosphates become docking sites, and the proteins that dock there start a kinase cascade "
canonical: https://lightmysky.com/learn/science/receptor-tyrosine-kinases-and-phosphorylation-cascades-mt_EvIwqsLVGA
source: https://lightmysky.com/learn/science/receptor-tyrosine-kinases-and-phosphorylation-cascades-mt_EvIwqsLVGA.md
retrieved: 2026-09-12
---

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# Receptor Tyrosine Kinases and Phosphorylation Cascades

Growth factor receptors pair up when a ligand binds, then phosphorylate each other on tyrosine residues. Those phosphates become docking sites, and the proteins that dock there start a kinase cascade that reaches the nucleus.

Subject: Science · Area: Organisms & Life Processes · Ages 19 to 21
Page: https://lightmysky.com/learn/science/receptor-tyrosine-kinases-and-phosphorylation-cascades-mt_EvIwqsLVGA

## Ready when they can

- Explains why dimerisation is the switch rather than just a consequence of binding.
- Says how a phosphate on a receptor recruits a specific partner rather than any protein.
- Predicts the effect of a receptor that dimerises without a ligand present.

## Lesson: Pair up, then pass it on

Growth factor receptors wait alone and inactive until a ligand joins two of them into a dimer. Each receptor by itself cannot phosphorylate anything, and only the paired dimer can. Dimerisation is the proof that a ligand is really there, so it works as the on switch rather than a side effect.

The paired receptors phosphorylate each other on tyrosine residues, and those phosphotyrosines become docking sites. Adaptor proteins with matching domains latch onto the docks, so a phosphate recruits a specific partner rather than any passing protein. Specificity lives in the fit between dock and domain.

**Example.** The docked proteins start a kinase cascade that reaches the nucleus. Each kinase switches on many copies of the next, so one active receptor produces a flood of active kinases at the end. Growth factor signalling shows the pattern: a small outside event becomes a large inside response.

**Tip.** Contrast this family with GPCRs, which pass the message through G proteins and second messengers while RTKs phosphorylate themselves and dock adaptors directly. A receptor that dimerises with no ligand would fire nonstop, with the cell behaving as if growth factor were always present. Phosphatases and receptor removal silence the path again.

**Recap.** Ligand pairs the receptors, phosphates dock the partners, and the kinase chain carries the order inward.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [G-Protein-Coupled Receptors and Second Messengers](https://lightmysky.com/learn/science/g-protein-coupled-receptors-and-second-messengers-mt_7ozcs_sUOJ)
- [Post-translational Modification and Protein Turnover](https://lightmysky.com/learn/science/post-translational-modification-and-protein-turnover-mt_93cxQwxxkh)

## Opens up

- [Oncogenes and Tumour Suppressors: Why One Allele Is Sometimes Enough](https://lightmysky.com/learn/science/oncogenes-and-tumour-suppressors-why-one-allele-is-sometimes-enough-mt_7WTgv1dLNx)
- [Signal Integration: Cross-talk, Feedback and Termination](https://lightmysky.com/learn/science/signal-integration-cross-talk-feedback-and-termination-mt_Io2P-l38Xq)