Cell Communication

ligand

signaling molecule that binds to a receptor

reception

The binding of a signaling molecule to a receptor protein, activating the receptor by causing it to change shape.

Transduction

process of converting external signal into a response by a series of interactions between molecules inside the cell

paracrine signaling

local signaling; secretory cell secretes signal to nearby target cells

endocrine signaling

A type of long-distance signaling that utilizes hormones as signaling molecules

Hormones

chemical signals that are secreted into the circulatory system and communicate regulatory messages within the body

synaptic signaling

a nerve cell releases neurotransmitter molecules into a synapse, stimulating the target cell

Kinases

Enzymes that add phosphate groups to target proteins by transferring phosphate from ATP to the target molecule.

Phosphatase

an enzyme that removes a phosphate from a protein

ligand-gated ion channel

Type of membrane receptor that has a region that can act as a "gate" when the receptor changes shape. The gate opens up when the ligand is bound to the receptor.

enzymatic receptors

receptor that catalyzes a reaction upon ligand binding (these are typically kinases)

G-protein coupled receptors

A special class of membrane receptors with an associated GTP binding protein; activation of a G protein-coupled receptor involves dissociation and GTP hydrolysis

second messenger

A small, nonprotein, water-soluble molecule or ion, such as calcium ion or cyclic AMP, that relays a signal to a cell's interior in response to a signal received by a signal receptor protein.

intracellular receptors

receptors located inside the cell rather than on its cell membrane; their ligands are lipid soluble

Receptor Tyrosine Kinases (RTKs)

a receptor protein spanning the plasma membrane once; the cytoplasmic part of which can catalyze the transfer of a phosphate group from ATP to a tyrosine on another protein; acts as a dimer

kinase cascade

A signaling pathway in which a protein kinase is activated by phosphorylation, and in turn phosphorylates the next protein kinase in the sequence; also called a phosphorylation cascade

Ras

GTP-binding protein (small G-protein) that is mutated in 30% human cancers;

trimeric G proteins

A large family of GTPases, consisting of three subunits (α, β and γ). The Gβ and Gγ subunits bind to each other very tightly but bind reversibly to Gα. The association of Gα with Gβγ and the activity of these subunits depend on whether GTP or GDP is bound to Gα. These proteins transduce signals from a family of receptor proteins known as G-Protein Coupled Receptors.