Signaling Pathways Overview

These flashcards cover key concepts and mechanisms of various signaling pathways discussed in the lecture notes.

What activates the enzyme adenylate cyclase in the cAMP pathway?

The Gs protein, a member of the G protein family.

What is the role of cAMP in the signaling pathway?

cAMP acts as a secondary messenger that activates protein kinase A (PKA).

What does PKA phosphorylate within cells?

PKA phosphorylates various target proteins, including ion channels.

How does the enzyme phosphodiesterase affect cAMP?

Phosphodiesterase breaks down cAMP, terminating the signal.

What are the two second messengers generated by phospholipase C (PLC) in the phosphoinositol pathway?

Diacylglycerol (DAG) and inositol-1,4,5-trisphosphate (IP3).

What is the function of the IP3 receptor?

It opens calcium channels in the smooth endoplasmic reticulum, allowing Ca²⁺ to flow into the cytosol.

What role does calmodulin (CaM) play in calcium signaling?

CaM activates various enzymes, including CaMKII, in response to elevated intracellular calcium.

What is Ras in the context of signaling pathways?

Ras is a small GTP-binding protein that acts as a molecular switch activation in the MAP kinase phosphorylation pathway.

What happens when Ras is activated by an activating protein?

Ras exchanges GDP for GTP, transitioning into its active state and initiating a phosphorylation cascade.

What do activated STAT proteins do in the JAK/STAT signaling pathway?

They migrate to the nucleus and stimulate the transcription of specific target genes.

How do SOCS proteins function in the regulation of the JAK/STAT pathway?

SOCS proteins negatively regulate JAK activity as part of a feedback loop.

What activates the NF-κB signaling pathway?

Various cell-surface receptors, including Toll-like receptors and cytokines like TNFα and IL-1.

What is the initial effect of TNFα binding to its receptor?

It induces a rearrangement that recruits signaling proteins and activates IκB kinase (IKK).

What is the function of Sonic hedgehog (SHH) in development?

SHH is involved in the regulation of digit identity during limb development.

Describe the interaction of Delta and Notch in the Notch signaling pathway.

Delta binds to Notch receptors on neighboring cells, triggering proteolytic cleavages that release the Notch intracellular domain (NICD) to activate transcription.