Chapter 6 – Signal Transduction (Sections 6.14–6.26)

Fourteen question-and-answer flashcards reviewing key signaling concepts, proteins, and messengers from Chapter 6 (sections 6.14–6.26).

What happens to a target protein after it is phosphorylated by a protein kinase?

It becomes either activated or inhibited.

How does a receptor–hormone complex alter gene expression?

By activating or inhibiting the transcription of a specific gene.

What is the primary function of myosin light chain kinase (MLCK) in smooth muscle cells?

It promotes the interaction of myosin and actin to cause contraction.

What is the state of a smooth muscle cell when MLCK is phosphorylated and inactive?

The cell relaxes because myosin and actin do not interact.

How does the entry of ions into a target cell generate a cellular response?

By changing the cell’s electrical properties, leading to excitation or inhibition.

Name two water-soluble extracellular messengers that bind to receptor tyrosine kinases.

Growth factors and insulin.

Which water-soluble messenger binds to a receptor guanylyl cyclase?

Atrial natriuretic peptide (ANP).

What enzyme family can be coupled to receptors and phosphorylates their cytosolic portions to create docking sites for STATs?

Janus kinases (JAKs).

What overall role does a G protein serve in signal transduction?

It acts as a relay protein that helps mediate the signaling pathway.

Which nucleotides can bind to the alpha (α) subunit of a G protein?

GDP or GTP.

Which specific type of G protein stimulates adenylyl cyclase?

Gs (the stimulatory G protein).

How does CREB-binding protein (CBP) facilitate transcription of a target gene?

By loosening chromatin structure and recruiting RNA polymerase.

What occurs when IP3 binds to its receptors on the endoplasmic reticulum?

IP3-gated channels open, releasing Ca²⁺ from the ER lumen into the cytosol.

Many neurotransmitters activate which type of signaling pathways to regulate ion channels?

G-protein signaling pathways.