Cell Signaling Part 2

Question 1

Are transmembrane proteins with their ligand-binding domain on the outer surface.

Answer 1

Enzyme-coupled Receptors

Question 2

How many transmembrane segments does enzyme-coupled receptors typically have?

Answer 2

One

Question 3

The extracellular region of an RTK where signal proteins (ligands) bind to activate the receptor

Answer 3

Ligand-binding domain

Question 4

The process where two RTKs pair up after ligand binding, enabling activation of their kinase domains

Answer 4

Dimerization

Question 5

Binding sites created on the cytosolic part of RTKs after phosphorylation, allowing intracellular signaling proteins to attach and relay the signal.

Answer 5

Phosphotyrosine Docking Sites

Question 6

A type of RTK where dimerization brings kinase domains together, allowing them to phosphorylate each other and fully activate.

Answer 6

Insulin Receptor

Question 7

Activated by conformational changes in the kinase domains caused by their interaction, rather than phosphorylation.

Answer 7

Epidermal Growth Factor (EGF)

Question 8

What activates the kinase domains of Epidermal Growth Factors Receptor?

Answer 8

Conformational changes

Question 9

Main Human Ras Proteins

Answer 9

H-Ras, K-Ras, and N-Ras

Question 10

A group of monomeric GTPases, including Ras and Rho families, that relay signals from cell-surface receptors to coordinate multiple signaling pathways.

Answer 10

Ras Superfamily

Question 11

Two classes of signaling proteins that regulate Ras activity:

Answer 11

1. Ras guanine nucleotide exchange factors (Ras-GEFs)
2. Ras GTPase-activating proteins (Ras-GAPs)

Question 12

Ras regulating protein that stimulate the dissociation of GDP and the subsequent uptake of GTP from the cytosol, thereby activating Ras

Answer 12

Ras guanine nucleotide exchange factors (Ras-GEFs)

Question 13

Ras regulating protein that increase the rate of hydrolysis of bound GTP by Ras, thereby inactivating Ras.

Answer 13

Ras GTPase-activating proteins (Ras-GAPS)

Question 14

Mutant forms of Ras that resist GAP-mediated inactivation, remaining locked in the active state and contributing to cancer.

Answer 14

Hyperactive Mutant Ras

Question 15

Two ways for RTKs to activate Ras

Answer 15

1. Activate Ras-GEFs
2. Inactivate Ras-GAPs

Question 16

An RTK in Drosophila required for forming the R7 photoreceptor, linked to Ras activation via Sos.

Answer 16

Sevenless (Sev)

Question 17

A Ras-GEF discovered in Drosophila, essential for activating Ras in the RTK signaling pathway.

Answer 17

Sos (Son-of-sevenless)

Question 18

Reverses tyrosine phosphorylations

Answer 18

Tyrosine-specific Protein Phosphatases

Question 19

Converts short-lived RTK and Ras signals into longer-lasting signals to relay them downstream to the nucleus for altering gene expression.

Answer 19

Mitogen-Activated Protein (MAP) Kinase

Question 20

Components of MAP Kinase Module

Answer 20

1. MAPK (Erk)
2. MAPKK (Mek)
3. MAPKKK (Raf)

Question 21

Enters the nucleus and phosphorylates components of transcription regulatory complexes, initiating immediate early gene transcription.

Answer 21

MAPK (Erk)

Question 22

Ras Activation of MAP Kinase Module

Answer 22

Ras activates MAPKKK (Raf), which phosphorylates and activates MAPKK (Mek), which then phosphorylates and activates MAPK (Erk)

Question 23

Genes activated within minutes of RTK signaling

Answer 23

Immediate Early Genes

Question 24

Ras–MAP-Kinase pathway

Answer 24

Conveys signals from the cell surface to the nucleus and alters the pattern of gene expression.

Question 25

Help prevent cross-talk between parallel MAP Kinase modules.

Answer 25

Scaffold Proteins

Question 26

MAP Kinase modules that are activated by diff. kinds of cell stresses (e. g., UV, heat shock, osmotic stress)

Answer 26

JNK & p38

Question 27

Functions of Scaffold Proteins

Answer 27

1. Avoid cross-talk of signaling pathways to ensure response specificity 2. Reduce amplification and spreading of signal to diff. parts of the cell

Question 28

Functions of Rho Family Monomeric GTPases

Answer 28

1. Regulate both the actin and microtubule cytoskeletons, controlling cell shape, polarity, motility, and adhesion. 2. regulate cell-cycle progression, gene transcription, and membrane transport 3. guidance of cell migration and nerve axon outgrowth

Question 29

Three best-characterized family members of the Rho Family

Answer 29

1. Rho 2. Rac 3. Cdc42

Question 30

Inactive Rho family GTPases are often bound to ________ in the cytosol.

Answer 30

Guanine nucleotide dissociation inhibitors (GDIs)

Question 31

Surface of motor neurons and helps guide the migration of the tip of the axon (called a growth cone) to its muscle target.

Answer 31

Eph family of RTKs

Question 32

Activates the Rho protein RhoA

Answer 32

Ephexin

Question 33

Controls cell fate choices and regulates pattern formation during the development of most tissues, as well as in the continual renewal of tissues.

Answer 33

Notch Receptor Protein

Question 34

When a precursor cell commits to becoming a neural cell and signals to its immediate neighbors not to do the same

Answer 34

Lateral Inhibition

Question 35

Transmembrane protein that activates contact-dependent signaling mechanisms

Answer 35

Delta

Question 36

A single-pass transmembrane protein that requires proteolytic processing to function; acts as latent transcription regulator

Answer 36

Notch Proteins

Question 37

The protease responsible for the final cleavage of the Notch tail.

Answer 37

γ-secretase

Question 38

are secreted signal molecules that act as local mediators and morphogens

Answer 38

Wnt Proteins

Question 39

Signaling pathways activated by Wnt Proteins

Answer 39

1. Wnt/β-catenin pathway 2. Planar polarity pathway

Question 40

Is centered on the latent transcription regulator β-catenin

Answer 40

Wnt/β-catenin pathway

Question 41

Coordinates the polarization of cells in the plane of a developing epithelium and depends on Rho family GTPases.

Answer 41

Planar polarity pathway

Question 42

Wnt/β-catenin pathway acts by regulating the proteolysis of the multifunctional protein _______ .

Answer 42

β-catenin

Question 43

A portion of the cell’s β-catenin is located at _______ and thereby contributes to the control of cell–cell adhesion

Answer 43

cell–cell junctions

Question 44

phosphorylates the β-catenin

Answer 44

casein kinase 1 (CK1)

Question 45

hold the protein degradation complex together

Answer 45

axin and Adenomatous polyposis coli (APC)

Question 46

Four proteins in the Protein degradation Complex:

Answer 46

1. casein kinase 1 (CK1) 2. glycogen synthase kinase 3 (GSK3) 3. Axin 4. Adenomatous polyposis coli (APC)

Question 47

Secreted signal molecules and act as local mediators and morphogens

Answer 47

Hedgehog Proteins

Question 48

Mutation of the Hedgehog gene produces a larva covered with _______ .

Answer 48

spiky processes (denticles)

Question 49

Three genes encode Hedgehog proteins in vertebrates

Answer 49

1. Sonic hedgehog 2. Desert hedgehog 3. Indian hedgehog

Question 50

The effects of Hedgehog are mediated by a latent transcription regulator called _______ .

Answer 50

Cubitus interruptus (Ci)

Question 51

Hedgehog works by preventing the proteolytic processing of Ci, converting it into a transcriptional activator. This process involves three transmembrane proteins:

Answer 51

Patched, iHog, and Smoothened

Question 52

Are latent transcription regulators that are present in most animal cells and are central to many stressful, inflammatory, and innate immune responses.

Answer 52

NFkB Signaling Pathway

Question 53

Five NFκB proteins in mammals

Answer 53

1. RelA 2. RelB, 3. c-Rel 4. NFκB1 5. NFκB2

Question 54

Inhibitory proteins called _____ bind tightly to the dimers and hold them in an inactive state within the cytoplasm of unstimulated cells.

Answer 54

IκB

Question 55

Three major IκB proteins in mammals

Answer 55

IκB α, β, and ε

Question 56

Cell-surface receptors that activate the NFκB signaling pathway

Answer 56

1. Toll Receptors (Drosophila) 2. Toll-like Receptors (vertebrates) 3. Tumor necrosis factor α (TNFα) 4. Interleukin-1 (IL1)

Question 57

Ligands that activate nuclear receptors:

Answer 57

1. Steroid hormones 2. thyroid hormones 3. retinoids 4. vitamin D

Question 58

The fundamental principle underlying circadian clock function is ________ .

Answer 58

Negative Feedback Loops

Question 59

Internal oscillators that control the diurnal rhythms that dictates different behaviors as different times of day.

Answer 59

Circadian clocks

Question 60

Controls the diurnal cycles of sleeping and waking, body temp, and hormone release.

Answer 60

SCN cells of the suprachiasmatic nucleus of the hypothalamus

Question 61

Circadian clock is characterized by the accumulation and decay of two transcription regulatory proteins:

Answer 61

1. Tim (Timeless) 2. Per (Period)