Mating Type a
A mating type in which cells secrete chemical signals called ;a; factor that bind to receptor proteins on nearby ;α; cells.
Mating Type α
α cells secrete α factor, which binds to receptors on a cells.
Cell that forms as a result of the fusion of the two opposite cell type that contains a combination of genetic resources that provides advantages to the cell's descendants.
Signal Transduction Pathway
A signal on the cell's surface is converted into a specific cellular response.
A chemical messenger that influences cells in the vicinity.
A class of local regulator that stimulate target cells to grow and multiply in plant cells. (Known as paracrine signaling in animal cells).
A type of local signaling in an animals nervous system in which an electrical signal along the nerve cell triggers the secretion of a chemical signal in the form of neurotransmitter molecules which stimulates the target cell by diffusing across the synapse.
The narrow space between the nerve cell and its target cell.
In multicellular organisms, one of many types of circulating chemical signals that are formed in specialized cells, travel in body fluids, and act on specific target cells to change their functioning.
Also known as hormone signaling; specialized cells in animals release hormone molecules into vessels of the circulatory system, which then travel to target cells in other parts of the body.
The stage in a cellular conversation in which the target cell detects a signal molecule coming from outside the cell because the signal has bind to a receptor protein on the cell's surface.
The second stage in a cellular conversation in which the binding of the signal molecule changes the receptor protein. The signal is converted into a form that brings about cellular response.
The third stage of a cellular conversation where the trandsduced singal triggers a cellular response.
Describes a molecule that specifically binds to other molecules, such as signal molecules.
Intracellular receptor proteins
Proteins found in the cytoplasm or nucleus of target cells.
Steroid hormones that are secreted by cells of the testis.
Special proteins that control which genes are transcribed into mRNA in a particular cell at a particular time.
G-protein linked receptor
A plasma membrane receptor that works with G proteins. These receptors are composed of have seven alpha helices spanning the membrane. They have roles in embryonic development and sensory reception.
A protein that functions as a molecular switch that is either on or off which is loosely attached to the cytoplasmic side of the membrane.
A substance that when bounded to the G protein makes it inactive.
GTP Guanosine triphosphate
The triphosphate that displaced the GDP when the appropriate signal molecule binds to the extracellular side of the receptor and activates it.
Receptor Tyrosine Kinase
A receptor protein in the plasma membrane that response to the binding of a signal molecule by binding of a signal molecule by catalyzing the transfer of phosphate groups from ATP to tyrosines on the cytoplasmic side of the receptor. The phosphorylated tyrosines activate other signal transduction proteins within the cell.
An enzyme that catalyzes the transfer of phosphate groups.
An enzyme that catalyzes the transfer of a phosphate group from ATP to the amino acid tyrosine on a substrate protein.
Signal Transduction Pathway
The first step in the chain of molecular interactions when the binding of a specific signal molecule to a receptor in the plasma membrane
Molecules, usually proteins, that relay a signal from receptor to response.
Describes an enzyme that transfers phosphate groups from ATP to a protein.
Serine and Threonine Kinases
Involved in signaling pathways in animals, plants, and fungi.
A series of different molecules in a pathway are phosphorylated in turn, each molecule adding a phosphate group to the next one in line. The addition of phosphate groups often changes a protein from an inactive form to an an active form.
Enzymes that rapidly remove phosphate groups from proteins.
When enzymes rapidly remove phosphate groups from proteins and inactivate protein kinase. The process also enables cells to respond again to extracellular signal.
Small, nonprotein, water soluble molecules or ions involved in signaling pathways that are able to readily spread throughout the cell by diffusion.
The extracellular signal molecule that binds to the membrane receptor.
Cyclic Adenosine MMonophosphate (cAMP)
A second messenger that carried the signal initiated by epinephrine from the plasma membrane of a liver or muscle cell into the cell's interior and brings about glycogen breakdown.
An enzyme embedded in the plasma membrane that converts ATP to cAMP in response to an extracellular signal (epinephrine).
An enzyme that converts the cAMP to AMP.
Hormones that triggers the formation of cAMP. When it binds to a specific receptor protein, the protein activates adenylyl cyclase.
Inhibitory G Protein
The protein activated when a a different signal molecule activates a different receptor.
A disease that is epidemic where water supply is contaiminated with human feces. The cholera toxin is an enzyme that modifies a G protein involved in regulating salt and water secretions since the G protein can not hydrolyze GTP and GDP.
Inositol triphosphate (IP3)
A second messenger that functions as an intermediate between certain nonsteroid hormones and a third messenger, a rise in cytoplasmic Ca 2+ concentration.
A second messenger produced by the cleavage of a certain kind of phospholipid in the plasma membrane.
Upon activation of phospholipase C by ligand binding to a receptor, what effect does the IP3-gated calcium channel have on Ca2+ concentration in the cytosol?
The IP 3 -gated channel opens, allowing calcium ions to flow out of the ER, which raises the cytosolic Ca 2+ concentration.
Cytoplasmic Response to a Signal
In this signaling system, the hormone epinephrine acts through a G-protein-linked receptor to activate a succession of relay molecules, including cAMP and two protein kinases. The final protein to be activated is the enzyme glycogen phosphorylase, which releases glucose-1-phosphate units from glycogen. This pathway amplifies the hormonal signal, because one receptor protein can activate about 100 molecules of G protein, and each enzyme in the pathway can act on many molecules of its substrate, the next molecule in the cascade
Nuclear Responses to a Signal
The initial signal molecule, a local regulator called a growth factor, triggers a phosphorylation cascade. Once phosphorylated, the last kinase in the sequence enters the nucleus and there activates a gene-regulating protein, a transcription factor. This protein stimulates a specific gene so that an mRNA is synthesized, which then directs the synthesis of a particular protein in the cytoplasm.
A type of large relay protein to which several other relay proteins are simultaneously attached to increase the efficiency of signal transduction.
When the absence of a single relay protein leads to such diverse effects as abnormal bleeding, eczema, and a predisposition to infections and leukemia.