Receptor signaling mechanisms

Learning objective

Trace a GPCR signal through a G protein to an effector and distinguish first from second messenger.

A relay instead of the receptor’s own pore

In the course’s GPCR example, ligand binding activates a receptor coupled to a G protein. Downstream signaling can affect a separate ion channel or an effector enzyme. The receptor is not itself the ion channel. This architecture permits effects beyond an immediate postsynaptic voltage change.

First and second messengers

The transmitter outside the cell is the first messenger in this account. An effector such as adenylyl cyclase can produce an intracellular second messenger such as cAMP. The slide then connects second messengers to protein kinases, substrate phosphorylation, and potentially transcription factors such as CREB and changes in gene expression. These are example branches, not a claim that every GPCR follows exactly this chain.

G protein-coupled receptor

A receptor that signals through a coupled G protein.

Second messenger

An intracellular signaling molecule produced downstream of receptor activation in the described pathway.

cAMP

Cyclic adenosine monophosphate, the deck’s example of a second messenger.

Receptor classification

Plasticity versus neurogenesis

Receptor Mechanism Lab

Professor deck 3, PDF pages 11, 12, 14. Explanation and terminology are paraphrased course material. Examples and study prompts are original, unscored teaching aids. Source conformance is separate from scientific or clinical review.

Worked examples are original instructional illustrations; they are not professor quotations or exam requirements.