CBIO3400 L23 – Signaling via Receptor Tyrosine Kinases (RTKs) #2

These flashcards cover the vocabulary and key concepts of Chapter L23, focusing on Receptor Tyrosine Kinase (RTK) activation, signaling complex formation, protein domains (SH2, SH3, PH), and the Ras/MAPK pathway.

Asymmetric Kinase Dimerization

The activation mechanism for hEGFR where the kinase domain of an activator protein pushes against the kinase domain of a receiver protein, inducing a conformational change in the receiver domain that enables phosphorylation.

Type #1 Intracellular Signaling Complex

A signaling complex characterized by fast signal transmission speed, little opportunity for signal amplification, and little to no cross-talk between pathways.

Type #2 Intracellular Signaling Complex

A signaling complex that assembles on an activated receptor; it has slow transmission speed unless kinase concentration is high, but offers great signal amplification and a high probability of cross-talk.

SH2 Domain

A compact, plug-in module or protein domain that specifically binds to phosphorylated tyrosine ($pTyr$) in the context of target peptides.

Protein Tyrosine Binding (PTB) Domain

A specific protein domain that recognizes and binds to phosphorylated tyrosine residues.

Src Homology 3 (SH3) Domain

A protein domain involved in protein-protein interactions that specifically binds to proline-rich regions or motifs.

Pleckstrin Homology (PH) Domain

A protein domain that binds to phosphorylated inositol lipids, such as those found on phosphoinositide docking sites.

Immunoprecipitation

Also known as pull-down assays, this technique investigates the direct interaction of two proteins by using antibodies bound to magnetic beads to isolate specific protein complexes.

Mitogen-activated protein kinase (MAPK)

A family of serine/threonine kinases whose activation involves phosphorylation as a key regulatory mechanism for transmitting signals that regulate proliferation, differentiation, and survival.

Grb2

An adaptor protein containing both SH2 and SH3 domains that links an activated RTK to the Ras GEF known as Son-of-Sevenless (SOS).

Son-of-Sevenless (SOS)

A protein containing a Ras GEF domain and a proline-rich region that facilitates the exchange of GDP for GTP on Ras proteins.

Ras

A small GTPase that acts as a molecular switch in signaling pathways, alternating between an inactive GDP-bound state and an active GTP-bound state.

FRET (in Ras visualization)

A single-molecule technique used to visualize the transient activation of Ras by measuring energy transfer between a yellow fluorescent protein (YFP) at $528\, \text{nm}$ and a red fluorescent dye at $617\, \text{nm}$.

Protein Domains

Distinctly folded parts of proteins that can often be separated while retaining their structure; they are frequently shuffled to generate new functionality in signaling pathways.