Part 4: Molecular Pharmacology

Drug Targets at the Molecular Level

Most drugs work by binding to specific molecular targets โ€” proteins that mediate cellular signaling. Understanding the four major receptor superfamilies and their signaling mechanisms is fundamental to predicting drug effects and designing new therapeutics.

Connection to Molecular Biology:

See Ion Channels for detailed structure and function of ligand-gated and voltage-gated channels.

Topics in This Part

4.1 G-Protein Coupled Receptors

7-TM structure, Gฮฑ/Gฮฒฮณ subunits, cAMP/IP3/DAG signaling

4.2 Ion Channel Receptors

Ligand-gated, voltage-gated, ionotropic receptor pharmacology

4.3 Enzyme-Linked Receptors

Receptor tyrosine kinases, JAK-STAT, growth factor signaling

4.4 Nuclear Receptors

Steroid hormones, thyroid, retinoic acid, transcription regulation

4.5 Second Messengers

cAMP, cGMP, Caยฒโบ, IP3, DAG, NO โ€” intracellular signaling cascades

4.6 Gene Expression

Transcription factors, epigenetics, long-term drug effects

Receptor Superfamilies

TypeResponse TimeMechanism
Ion ChannelsMillisecondsDirect ion flux
GPCRsSecondsG-protein โ†’ second messengers
Kinase-linkedMinutesPhosphorylation cascades
NuclearHoursGene transcription
โ† Part 3: Pharmacodynamics4.1 GPCRs โ†’