Cell Bio Cell Campbell Chapter 11 Cell Communication

Front 1

Signal transduction pathway

Back 1

Process by which signal on the cell surface is converted into a specific cell response

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local regulator

Back 2

influences local cells

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paracrine

Back 3

single cell produces growth factor that stimulates growth of local cells.

Front 4

autocrine

Back 4

is a form of signaling in which a cell secretes a chemical messenger (called the autocrine agent) that signals the same cell.

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3 steps from cell signal to response

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1) Reception - detects signal. 2) Transduction - binding of a signal molecule changes the receptor protein. Transduction converts the signal to a form that can bring about a specific cellular response. 3) Response

Front 6

G protein-linked receptors

Back 6

plasma membrane receptors that work with the help of a G protein. Made of 7 alpha helices spanning the membrane. Cytoplasmic side is the G protein which acts like a switch binding either GDP or GTP. When GDP is bound it is inactive.

Front 7

Tyrosine Kinase receptors

Back 7

Designed to simulate more than one pathway at once. Tyrosine kinase on cytosolic side transfers phosphate from ATP to tyrosine. Has a single alpha helix binding site extracellularly. Cytosolically it has multiple tyrosine kinase receptor proteins.

Front 8

Steps to activation of tyrosine kinase

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Ligand binds causing 2 receptor polypeptides to form a dimer. Aggregation activates tyrosine kinase parts to add phosphates to tyrosine in the tail of the other. Now activated it is a recognized by relay proteins. Each binds to a special phosphorylated tyrosine undergoing structural changes that activates them.

Hint 8

None

Front 9

Ligand gated ion channels

Back 9

protein pores that open to allow ions through. These are important in transmission of electrical signals down neurons or muscle fibers.

Front 10

Intracellular receptors

Back 10

lipid soluble hormones and others that can diffuse through the cell membrane bind to cytosolic receptors activating them and are then transported into the nucleus. The cell is signal physically brought into the nucleus rather than having a relay chemical.

Front 11

Protein kinase

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transfers phosphate groups from ATP to a protein. Usually a protein kinase transports their substrates onto serine or threonine.

Front 12

Many of the molecules in signal transduction pathways are protein kinases and they often act on each other.

Front 13

Second messenger

Back 13

part of the signal transduction pathway. Small water soluble non-proteins. cAMP and Ca2+ are second messengers.

Front 14

Cyclic AMP

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second messenger. Immediate effect is usually the activation of a serine/threonine kinase called protein kinase A

Front 15

Adenylyl cyclase

Back 15

enzyme built into the plasma membrane that converts ATP to cyclic AMP in response to an outside stimulation.

Front 16

Further fine tuning of metabolism is provided by other G protein systems that inhibit adenylyl cyclase.

Front 17

Diacylglycerol (DAG)

Back 17

second messenger created by a cleavage of a phospholipid in the plasma membrane

Front 18

Inositol triphosphate (IP3)

Back 18

second messenger created by a cleavage of a phospholipid in the plasma membrane. Stimulates the release of Ca2+ from the ER.

Front 19

Calmodulin

Back 19

Ca2+ binding protein found in high levels in animal cells (up to 1% of animal protein). Mediates many Ca2+ regulated processes. When Ca2+binds calmodulin changes shape and binds to other proteins activating or inactivating them.

Front 20

dimer

Back 20

a molecule composed of two identical subunits or monomers linked together. The molecules are connected with a covalent bond or more weak interactions such as hydrogen bond.