Lecture 11 Flashcards Preview

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Flashcards in Lecture 11 Deck (12):
1

adenylyl cyclase

converts ATP to cAMP

2

cyclic AMP (cAMP)

diffuses through the cell and activates a serine/threonine kinase, called protein kinase A,which phosphorylates other proteins

3

G-protein-linked receptor

consists of a receptor protein associated with a G-protein on the cytoplasmic side.
? The receptor consists of seven alpha helices spanning the membrane.
? Effective signal molecules include yeast mating factors, epinephrine, other hormones, and neurotransmitters.

4

hormone

Plants and animals use hormones to signal at greater distances

5

ligand-gated ion channel

are protein pores that open or close in response to a chemical signal.

6

ligand

small molecules that bind specifically to a larger molecule

7

local regulator

? Some transmitting cells release local regulators that influence cells in the local vicinity

8

protein kinase

Most protein kinases act on other substrate proteins, unlike the tyrosine kinases that act on themselves

9

scaffolding protein

Rather than relying on diffusion of large relay molecules like proteins, many signal pathways are linked together physically by scaffolding proteins

10

second messenger

? Pathways initiated by both G-protein-linked receptors and tyrosine-kinase receptors involve small, nonprotein, water-soluble molecules or ions, called second messengers.
? These molecules rapidly diffuse throughout the cell.
? Two of the most important are cyclic AMP and Ca2+.

11

signal-transduction pathway

The process by which a signal on a cell?s surface is converted into a specific cellular response in several steps called a signal-transduction pathway

12

tyrosine-kinase receptor

? A individual tyrosine-kinase receptors consists of several parts:
? an extracellular signal-binding sites
? a single alpha helix spanning the membrane
? an intracellular tail with several tyrosines

? When ligands bind to two receptors polypeptides, the polypeptides aggregate, forming a dimer.
? This activates the tyrosine-kinase section of both.
? These add phosphates to the tyrosine tails of the other polypeptide.

? The fully-activated receptor proteins activate a variety of specific relay proteins that bind to specific phosphorylated tyrosine molecules.
? One tyrosine-kinase receptor dimer may activate ten or more different intracellular proteins simultaneously.
? These activated relay proteins trigger many different transduction pathways and responses