BI 222 Topic 3

Autocrine

Self target

Cell produces a signaling protein to make something.

Gab junction

protein channel

protein tunnel through two cells so they can send signals to one another or smaller items like Ca⁺ ions.

Paracrine

Nearby Cell

cell targets nearby cell, but it has to diffuse slightly to send these signals, cells are not directly touching.

Endocrine

Distant cell, via the blood.

Targets specific cells and must circulate in the blood. Stays in the body!

Exocrine

Many types, usually part of the digestive system to excrete items from the body.

How many steps does Signal Transduction and Cell Signaling have?

3 stages.

Reception

Propagation

Response

Signal Transduction and Cell Signaling

1 Reception

ligand (signaling molecule) will bind to the receptor.

Signal Transduction and Cell Signaling

2 Propagation

Internal targets are activated

Signal Transduction and Cell Signaling

3 Response

Final target activated, causing cellular change.

Ligand

Small diffusible item that binds a receptor

example: hormones in the blood!

G protein

protein that binds and hydrolyzes GTP into GDP

GDP is typically considered?

OFF

GTP is typically considered?

ON

Kinase

Enzyme that phosphorylates another protein.

Phosphorylation means?

Adding a Phosphate group!

Kinase brings the P to the party.

Phosphatase

Enzyme that removes a phosphate. (Dephosphorization)

Internal Receptors

Receptors that reside within the cytoplasm.

What is required of ligands when it comes to internal receptors?

small nonpolar ligands must pass through the PM

Examples of internal receptor?

Estradiol and testosterone.

What happens after a internal receptor is activated?

It heads to the nucleus.

(After the assassin infiltrated the outside gates, he headed to the king’s chamber.)

Internal receptor often act as what?

Transcription factors.

Ligand Gated Ion Channel

Ligand Binds

Gate Opens

Ion diffuses down the concentration gradient

Common example of Ligand Gated Ion channel?

Acetylcholine and Na⁺

That work as a neuro transmitter

Voltage Gated Ion Channel

Certain amounts of +/- charge will open the protein channel gate and let ions diffuse down their concentration gradient.

G Protein Coupled Receptors

Receptor associated with G protein

Has 2 main classes - Small G protein, and heterotrimeric

G Protein Coupled Receptors

1 Small G protein

1 subunit that does everything

Example: RAS - associated with receptors

G Protein Coupled Receptors

2 - Heterotrimeric

alpha, beta, gamma

What step of the G Protein Coupled Receptors Cycle is this?

The receptor has the GDP and is waiting for the signaling ligand.

What step of the G Protein Coupled Receptors Cycle is this?

When the signaling ligands binds to the G Protein and activates the alpha heterotrimeric G protein into swapping GDP for GTP ( turning it on)

What step of the G Protein Coupled Receptors Cycle is this?

The Alpha part of the heterotrimeric disassociates from the gamma and beta and sends out a signal response.

What step of the G Protein Coupled Receptors Cycle is this?

The GTP is hydrolyzed back into GDP (turning it off)

Tyrosine Kinase Receptor is a type of what?

Amino Acid

Propagation of Signal

Amplify and spreads out response

Protein activation (phosphorylation and dephosphorization)

Second messengers are?

Small items produced in large amounts that amplify signals

Ca⁺ is a second messanger to what?

Muscles in a reticulum → released to stop muscle contraction

One MEK can phosphorize how many ERK?

10

IP₃ is created by what?

PLC

cAMP

Cyclic AMP

Response includes modifications and changes to?

Gene expression

Cell metabolism

Cell growth

cell death (apoptosis)

IR

Insulin Receptor

Type: Tyrosine Kinase Receptor

IRS-1

IR Substrate

PKC

Protein Kinase C

GluT-4

channel protein that brings in glucose down the concentration gradient.

(facilitated diffusion)

PP1 -

Protein Phosphetase 1

-removes a phosphate group from glycogen synthase

GS

glycogen synthase

dephospholized = on/active

Glucagon Receptor (GPCR)

G-Protein Coupled receptor

GP (1st)

G Protein- Inactive bound to GDP, active with GTP

(You stay inactive sleeping on the couch with your dog, but active when running away from a tiger.)

AC

Adenylyl Cyclase - Converts ATP into cAMP

PKA

Protein Kinase A → activated by cAMP

PK

Phosphorylase Kinase

Activated by phosphorylation from PKA

(You take the A from PKA to activate the PK)

GP (2nd)

Glycogen Phosphorylase-

Activated by phosphorylation from PK. Hydrolyzes glycogen into glucose.