Cell Communication

Direct Contact

Type of cell communcation that is local via gap junctions or direct contact between cells

Paracrine Signaling

Type of cell communcation that is local via secretion of a chemical signal

Synaptic Signaling

Type of cell communication via local secretion of neurotransmitters by a neuron into a synapse with another neuron

Endocrine Signaling

Type of cell communication also known as hormone signaling. Long distance comm via secretion of hormones into the bloodstream.

Ligands

Any chemical that binds to specific protein receptor

Lipophilic/Hydrophobic (Non-Polar) Ligands

Ligands that can diffuse through the phospholipid bilayer and bind to a cytosolic or nuclear receptor to generate response in the cell.

Cytosolic Receptors

Receptor that can modify gene expression within the nucleus or alter existing ones

Nuclear Receptors

Receptor that can turn genes on or off, regulating protein synthesis

Lipophobic/Hydrophilic (Polar) Ligands

Ligands that are unable to diffuse through the bilayer and bind to receptor proteins on the membrane to transduce the signal without entering.

Chemically-Gated Ion Channels

Channel that open or close when the ligand binds to the channel protein

Enzyme-Linked Receptors

Receptors embedded in the plasma membrane with their catalytic site exposed inside the cell

Protein Kinases

Enzymes that phophorylate proteins, or activate other proteins

Phosphorylation

The process of activating a protein by the addition of a phosphate group, usually donated by ATP

Receptor Tyrosine Kinase (RTK)

Most common enzyme linked receptor typically used by insulin to initiate glucose diffusion and growth factos for mitosis and cell division

Signal Transduction

The process where chemical signals are communicated through molecular chains in the stages of Reception, Transduction, and Response

Reception

First stage of signal transduction where an extracellular ligand binds to and activates a membrane receptor

Transduction

Second stage of signal transduction where the activated membrane receptor turns on its associated proteins and starts a cascade of second messengers

Response

Last stage of signal transduction where the final second messenger acts on intracellular targets to create a response.

Second Messengers

Molecules and ions that transmit the message within the cell, the most common being cAMP and IP3/C²⁺