Cell Signaling: JAK-STAT and RTK Pathways

Erythropoietin (Epo) binding to two Epo receptors triggers dimerization, bringing JAK kinases closer and activating them via autophosphorylation.

Autophosphorylation, specifically of the activation loop, activates the JAK kinase's ability to phosphorylate other molecules.

JAK kinases are tyrosine kinases, meaning they specifically phosphorylate tyrosine residues, key step for relaying signals.

Epo receptors have three functional domains: extracellular, transmembrane, and cytosolic, each with specific roles in signaling.

Binding of Epo starts a cascade of events, including phosphorylated docking sites (phosphorylation for protein interactions), leading to a cellular response in erythrocyte progenitor cells.

SH2 domains bind to specific sequences on target proteins with high affinity if the target tyrosine is phosphorylated, but with low affinity if it is unphosphorylated.

Specific protein regions that link two different proteins together.

Protein binding that can be turned on and off, like turning a switch.

A protein that controls gene activity related to red blood cell production (erythropoiesis).

This triggers a chain of events, ultimately resulting in red blood cell development, including the activation of STAT5.

A protein that links other proteins together in a signaling pathway.

An adaptor protein with multiple protein-protein interaction domains that assemble proteins in an ordered series.

A protein domain that binds to phosphorylated tyrosine residues.

A protein domain that binds to proline-rich domains on other proteins.

A GTP-binding protein that regulates cellular signaling pathways and has intrinsic GTPase activity.

A type of cell surface receptor that activates signaling pathways when it binds to a specific ligand.

A small protein involved in cell signaling. It acts as a molecular switch by cycling between an active (GTP-bound) and inactive (GDP-bound) state.

The process where two identical RTK receptor molecules bind to each other after ligand binding, forming a dimer. This is crucial for initiating the signaling cascade.

When RTKs get activated, they add phosphate groups to themselves (autophosphorylation). This activates the receptor and creates docking sites for other proteins.

Ras is a key player in relaying signals from RTKs to further downstream pathways, ultimately influencing cell growth, differentiation, and survival.

Ligand binding to Receptor Tyrosine Kinases (RTKs) triggers their activation, leading to phosphorylation events that initiate signal transduction.

A series of protein-protein interactions that relay signals from the cell surface to intracellular targets, often involving phosphorylation cascades.

A signaling pathway involved in regulating cell growth, proliferation, and differentiation.

A signaling pathway crucial for cell survival, growth, and metabolism.

A signaling pathway linked to various cellular responses, including calcium mobilization and cytoskeletal rearrangements.