Day 16 Cell Communication

Why do cells communicate with each other and with their environment?

To coordinate responses between cells

Respond to the environment

Neurons secrete what type of molecules to bind to receptors to other neurons

Neurotransmitters

What does glucose signal yeast cells to do

Increase glucose transporters and enzymes for efficient uptake

What are the five ways cells communicate with each other?

Cell junctions, contact-dependent, autocrine, paracrine, endocrine

Which is the lecture's example of signaling through cell junctions?

Gap junctions connecting cardiac muscle cells

What is contact-dependent signaling, and what is the example?

Molecules bound to the surface of one cell signal cells that touch it

Ex. T cell signaling

Direct intercellular signaling

Gap junctions connecting cardiac muscle cells

Contact dependent signaling

Molecules bound to surface of cells serve as signals to cells coming in contact with them

Autocrine signaling - what can it be used to monitor

Monitors cell density and crowding

Autocrine signaling

Cells secrete signaling molecules that bind to their own cell surface

Autocrine signaling target

Self

Paracrine signaling

Signal does not affect originating cell, but does influence nearby cells

Paracrine signaling target

Neighboring cells

Cells releasing molecules to guide neurons to form circuit

Paracrine signaling

Endocrine signaling

Hormones secreted from endocrine organs carried through blood over long distances

Receptor activation

Signaling molecule binds to receptor

Signal transduction

Activated receptor stimulates a sequence of changes

Cellular response

Enzyme activity change

Function of structural proteins change

Gene expression change

Ligand

Signaling molecule that non-covalently binds a receiving molecule receptor

What is a cognate receptor, and what does 'occupied' mean?

The receptor specific for a certain ligand

A receptor that is occupied is bound to its ligand already

Receptor

Protein that receives a signal ligand

Cognate receptor

The receptor specific for a certain ligand

Occupied

A receptor bound to its ligand

Receptor affinity

How likely the ligand is to interact with the receptor

The binding relationship between ligand in solution and receptors

Dissociation constant, Kd

Kd = [Ligand][Receptor] / [Ligand-Receptor complex]

= koff / kon

Lower Kd means ligand stays bound ____ readily; lower/higher affinity

More; higher

Co-receptors

Help stabilize/facilitate ligand-receptor interaction via physical interaction with the receptor

Receptor mediated endocytosis

Reduce the density of receptors on their cell surface

Desensitization

Alterations to the receptor that lower its affinity for the ligand

Phosphorylation

Add phosphate group to molecule acting as off switch

Agonists

Drugs that activate the receptor they bind to

Antagonists

Bind receptors without triggering a change, and prevent the naturally occurring messenger from activating the receptor

After receptor conformation or clustering

Preprogrammed sequence of events