Molecular Signaling Within Neurons Part 1

How do activated intracellular receptors produce new mRNA?

1)Signal molecule binds to the receptor 2)Inhibitory complex dissociates from the the receptor, exposing DNA binding domain 3)This activated receptor form then travels into the nucleus 4)It can then alter transcription

--- act only upon physical contact with the target cell.

Cell-associated molecules

3 classes of signal molecules

Cell-impermeant, cell-permeant, and cell-associated molecules

The Response

Changes in the chemical properties if the effector molecules

3 simplified steps of chemical signaling

Conduction, Transmission and Transduction

Recpetor

Either metabotropic or ionotropic. Transduces the information of the neurotransmitter

Cell-Associated Molecules

Membrane bound on the extracellular surface- also called cell attached. Act only upon physical contact with the target cell. -Examples: integrins, neural cell adhesion molecules

Cell-impermeant molecules

Molecules are rapidly metabolized or internalized by the cell that releases it or a neighboring glial cell. -Short lived -examples: neurotransmitters, peptide hormones

Paracrine signaling

Over a longer distance, the secretion of chemical signals onto a group of target cells

Effector Molecule

The target protein of the receptor and signal. Mediates the intracellular pathways.

synaptic transmission

at a synapse- the transfer of information from one neuron to the next

--- are insoluble in aqueous solutions and may persist for hours or days.

cell-permeant molecules

Binding of signaling molecules causes a --- which triggers a --- within the cell.

conformational change; signaling cascade

Intracellular Receptors

lead to activation of signaling cascades that produce new mRNA and protein within the target cell.

Channel-Linked Receptors

ligand-gated ion channels that mediate direct neurotransmitter action. Ion flux changes membrane potential of the target cell.

G-protein coupled receptors

metabotropic receptors; regulate the intracellular contains of the target cell via a transducing molecule such as GTP binding protein

Enzyme-Linked Receptors

participate in cell signaling through extracellular ligand binding and initiation of second messenger cascades

Endocrine Signaling

secreted molecules diffuse into the bloodstream and trigger responses in target cells anywhere in the body

The component that produces a signal

the signaling cell with the signal (neurotransmitter)

Cell-permeant molecules

transported by carrier proteins in blood and other extracellular fluids. -Examples: steroid hormones, thyroid hormone, retinoids