Cell Signaling

Identify the advantages and disadvantages of scaffold protein organization of kinase cascades. -A physically arranged sequence is more efficient -Reduces the amplification effect of the kinase cascade -Allows the segregation of signaling modules

-Advantage -Disadvantage -Advantage

Which of the following are the three subclasses of membrane receptors?

-Channel-linked receprors -Enzymatic receptors -G protein-coupled receptors

Which of the following are ways in which intracellular receptors can act?

-They can be enzymatic receptors that modify molecules in the cytoplasm. -They can act by producing changes in gene expression.

Which of the following statements about the interaction between receptors and signaling pathways is true?

A GPCR and a RTK can activate the same signaling pathway.

What do we call proteins that act as a link between a receptor and proteins that initiate downstream signaling?

Adapter proteins

The enzyme that produces cAMP from ATP is called _________ ___________.

Adenylyl cyclase

How are animal and plant receptor kinases different?

Animals have tyrosine receptor kinases, plant receptor kinases are serine/threonine kinases.

Some cells send signals to themselves by secreting molecules that bind to receptors in their own plasma membranes. What is this known as?

Autocrine signaling

Membrane receptors typically belong to one of three subclasses: __________-linked receptors, ________ receptors or G-_________ coupled receptors.

Channel, Enzymatic, Protein

The action of PKA phosphorylating glycogen synthase leads to which of the following?

Decreased glycogen synthesis

The two basic mechanisms that can inactivate RTK's are which of the following?

Dephosphorylation, Internalization

In _________ contact, the signal is a molecule located in the plasma membrane of one cell, while the receptor protein is located in the plasma membrane of another, adjacent cell.

Direct

The type of cell communication characterized by the interaction of a signal molecule in the plasma membrane of one cell and a receptor protein in the plasma membrane of an adjacent cell is called which of the following?

Direct contact

Choose the four general types of cell communication?

Direct contract, paracrine signaling, endocrine signaling, and synaptic signaling

True or false: A signal transduction module can only be activated by a specific type of receptor.

False

________ proteins link GPCRs with effector proteins.

G

Which of the three types of membrane receptors acts indirectly via a "helper" molecule?

G protein-coupled receptors

How are G protein-coupled receptors different from enzymatic receptors?

G protein-coupled receptors act indirectly with the help of an assisting protein.

What proteins can bind GTP and GDP?

G proteins

Cell surface or membrane receptors bind this type of ligand.

Hydrophilic

Intracellular receptors bind this type of ligand.

Hydrophobic

Where do second messengers relay signals?

Inside the cell

When PKA phosphorylates glycogen synthase, what happens to the function of this enzyme?

It is inhibited.

A signaling molecule is known as which of the following?

Ligand

What term is used to describe a signaling molecule?

Ligand

MAP kinases are activated by which of the following?

Mitogens

A process in which one molecule fits specifically based on its complementary shape with another molecule is called which of the following?

Molecular recognition

Intracellular receptors are usually located in the ___________ or in the _________.

Nucleus, Cytoplasm

The four kinds of cell communication (between two different cells) based on the distance from source to receptor are: direct contact, __________ signaling, _________ signaling, and _______ signaling.

Paracrine, endocrine, synaptic

The addition or removal of which group is a major source of control for protein function during signal transduction?

Phosephate

The small GTP-binding protein that links the RTK with the MAP kinase cascade is known as which of the following?

Ras protein

Which of the following statements about receptors is true?

Receptors can have several subtypes/isoforms in the same organism.

What function does the relay protein Ras have in the signal transduction pathway?

Relay cellular signals to proteins that form the protein kinase cascade

What are the five groups in the GPCR family?

Rhodopsin, Secretin, Adhesion, Glutamate, and Frizzled/Taste 2

The ____________ ____________ __________ protein binds to each kinase in a protein kinase cascade, organizing them so each substrate is next to its enzyme.

Scaffold

Different cells can respond to the same signaling molecule in a completely (sometimes opposite) different way because they can have different __________ ___________ pathways associated with that signaling molecule.

Signal transduction

Which of the following are the two typical locations of intracellular receptors in the cell?

The nucleus and cytoplasm

Which of the following best summarizes the function of G proteins?

They link GPCRs with effector proteins.

Which of the following statements regarding signal transduction pathways (abbreviated SDP below) and the response of different cells to the same signal is true?

Two different cells can have different SDPs which allows them to respond differently to the same signaling molecule.

Autophosphorylation occurs when which of the following occurs?

Two receptor-ligand complexes associate and phosphorylate each other

In ________ signaling, a cell sends a signal to itself, by secreting molecules that bind to receptors in its own plasma membrane.

autocrine

The process of _________ occurs when two receptor-ligand complexes associate together and phosphorylate each other.

autophsophorylation

Adenylyl cyclase is an effector protein that produces the second messenger _________.

cAMP

Intracellular receptors usually act by changing gene ________ in the cell.

expression

Intracellular receptors usually act by changing gene __________ in the cell.

expression

Dephosphorylation and ________ are the two basic mechanisms that can inactivate receptor tyrosine kinases.

internalization

Small molecules or ions that relay signals inside the cytoplasm are called second ____________.

messengers

Signaling molecules that stimulate a cell to divide are called which of the following?

mitogen

The addition or removal of phosphate groups allow cells to control the function of _________.

proteins

Adapter proteins bind to phosphotyrosines and act as a link between a ________ and proteins that initiate downstream signaling.

receptor

The interaction of a receptor with its ligand is an example of molecular ___________.

recognition

In animals, receptor kinases are usually ________ kinases; in contrast, plant receptors kinases belong to the __________ -threonine type.

tyrosine, serine