Enzyme-Linked Receptors and Signaling Pathways Quiz

Which of the following best describes enzyme-linked receptors?

• They have intrinsic enzymatic activity or are associated with enzymes.

• They transmit signals via ion flow across the membrane.

• They are exclusively G-protein-coupled receptors (GPCRs).

• They bind steroid hormones and act as transcription factors directly.

The most common type of enzyme-linked receptor is the:

• Ion channel-linked receptor

• G-protein coupled receptor (GPCR)

• Receptor tyrosine kinase (RTK)

• Nuclear receptor

Upon ligand binding, receptor tyrosine kinases typically:

• Hydrolyze ATP directly to open a channel.

• Undergo dimerization and autophosphorylation.

• Immediately bind to G-proteins for downstream signaling.

• Dissociate from the membrane.

The role of phosphorylation in receptor tyrosine kinase activation is to:

• Create docking sites for downstream signaling proteins.

• Prevent further signal transduction.

• Promote receptor internalization immediately.

• Block ligand binding.

Which of the following is NOT typically a downstream pathway of RTK activation?

• MAPK pathway

• PLC pathway

• PI3K pathway

• Gs protein

Which domain of an RTK is responsible for phosphorylation of tyrosine residues?

• Extracellular ligand-binding domain

• Transmembrane domain

• Intracellular kinase domain

• G-protein binding domain

Activation of the PI3K pathway primarily leads to:

• Apoptosis and cell death

• Increased membrane potential

• Enhanced cell survival and metabolism

• Increased nuclear import of G-proteins

The enzyme phospholipase C-γ (PLC-γ), when activated by RTKs, cleaves which molecule?

• cAMP

• Phosphatidylinositol 4,5-bisphosphate (PIP2)

• Phosphatidylserine

• ATP

Which second messenger produced by PLC-γ is directly responsible for triggering calcium release from the endoplasmic reticulum?

• DAG

• cAMP

• IP3

• Akt

The MAPK pathway is typically activated through which small GTPase?

• Ras

• Rab

• Rho

• Ran