Second Messengers in Signal Transduction — Flashcards

Flashcard 1: Protein kinase G activates the enzyme _____, which dephosphorylates myosin light chain causing smooth muscle relaxation

Answer: phosphatase

Flashcard 2: In the adenylyl cyclase mechanism of cellular signaling, the second messenger _____ activates protein kinase A, which then phosphorylates specific proteins to produce physiologic actions

Answer: cAMP

Flashcard 3: Gi proteins _____ the cAMP signaling cascade

Answer: inhibit

Flashcard 4: In the phospholipase C mechanism of cellular signaling, the _____ generated from PIP2 causes release of Ca2+ from intracellular stores in the endoplasmic or sarcoplasmic reticulum

Answer: IP3

Flashcard 5: Once nitric oxide diffuses into muscle cells, it activates soluble (cytosolic) guanylyl cyclase, which converts _____ to cGMP

Answer: GTP

Flashcard 6: Binding of atrial natriuretic peptide to its receptor guanylyl cyclase causes conversion of _____ to cGMP

Answer: GTP

Flashcard 7: Gq proteins _____ the IP3-DAG signaling cascade

Answer: activate

Flashcard 8: Activation of a **GPCR** involves the exchange of _____ for _____ on the Gα subunit, leading to its dissociation from the Gβγ complex.

Answer: GDP

Extra: The Gα subunit possesses intrinsic GTPase activity, which hydrolyzes GTP back to GDP to terminate the signal. The GPCR itself acts as a Guanine nucleotide Exchange Factor (GEF) upon ligand binding.

Flashcard 9: _____ is the only known member of the CX3C chemokine group.

Answer: Fractalkine

Flashcard 10: Cyclin _____ and Cyclin E-CDK2 drive cells from G1 to S phase

Answer: D-CDK4/CDK6