Membrane Receptors and Endocytosis – Study Guide & Flashcards

These flashcards cover key concepts related to membrane receptors and signaling pathways, including hormone types, receptor mechanisms, and the effects of specific toxins on signaling.

What are the six general steps in cell signaling?

Synthesis, release, transport, receptor binding, cellular response, termination.

How do autocrine and paracrine signaling differ?

Autocrine acts on the same cell; paracrine acts on nearby cells.

What are the four hormone types?

Steroid, amine, peptide, and polypeptide.

From what molecule are steroid hormones derived?

Cholesterol.

What are the three major steroid hormone classes?

Corticosteroids, androgens, estrogens.

How do steroid hormones act on target cells?

Bind intracellular receptors → regulate gene expression.

What type of receptors do peptide hormones bind to?

Cell surface receptors.

What molecule is the precursor of eicosanoids?

Arachidonic acid.

What enzyme family produces prostaglandins from arachidonic acid?

Cyclooxygenases (COX-1 and COX-2).

How do NSAIDs relieve pain and inflammation?

Inhibit COX enzymes → reduce prostaglandin synthesis.

What are the four main classes of cell-surface receptors?

GPCRs, ion-channel receptors, tyrosine kinase-linked receptors, and intrinsic enzymatic receptors.

What second messenger does adenylate cyclase produce?

cAMP.

How is a G-protein signal terminated?

GTP hydrolysis by the α-subunit.

What effect does cholera toxin have on G-protein signaling?

Locks Gα in active GTP-bound form → continuous cAMP production.

How does pertussis toxin alter signaling?

ADP-ribosylates Gα → increases cAMP and disrupts cell regulation.

Which receptor uses acetylcholine and calcium ions for muscle contraction?

Ion-channel receptor (nicotinic acetylcholine receptor).

What receptor does botulinum toxin disrupt?

Acetylcholine receptor (ion-channel receptor).

What are the two types of tyrosine-related receptors?

Tyrosine kinase-linked and intrinsic enzymatic activity receptors.

What differentiates intrinsic enzymatic receptors from kinase-linked ones?

Intrinsic receptors have built-in kinase activity; linked receptors depend on associated kinases.

Give an example of a hormone using a GPCR.

Epinephrine or glucagon.

Give an example of a hormone using an intrinsic enzymatic receptor.

Insulin or growth factors.