Signal Transduction

What is the importance of signal transduction?

Cellular/physiological response

Understanding mechanisms and treatment approaches

Mis-regulation leads to disease

How far can signals be conducted?

Dependent on the type of transduction

Types of signaling

Contact-dependent, paracrine, synaptic, endocrine

Contact dependent signaling

Signaling molecule isn't secreted, rather makes direct contact with target cell receptor; immune response

Paracrine signaling

Signal secreted and received by peripheral cells; inflammation response, local mediation

Synaptic signaling

Nerve cell releases neurotransmitter molecules into a synapse, stimulating the target cell; neurotransmitters

Endocrine signaling

Signal is released into the bloodstream and travels to the target cell; hormones

How quickly do signals change behavior of target cell?

Dependent on mechanism

Which response is quicker, epinephrine mediated heart stimulation or growth factor mediated cell growth?

Epinephrine; the required proteins are already present

Pathway of epinephrine proteins

DNA > cRNA> protein, stored in cell > alters cytoplasmic machinery when activated

3 steps of signal transduction

Reception, transduction, response

Reception

Extracellular signal molecule is received by receptor protein

Transduction

Cell beings synthesizing signaling proteins to pass along message

Response

Effector proteins activate and respond; response is varied based on target tissue

Why are signals considered "Second messengers"

Lead to changes inside the cell; ex. cAMP, cGMP, DAG, IP3

What are the first messangers?

Hormones, growth factors, environmental stimuli; extracellular stimuli signaling change outside the cell

Effector proteins

Biological or cellular response to intracellular change

Signals

Proteins, peptides, amino acids, steroids, fatty acid derivatives, light, odor/scent, sound, gases