CELL SIGNALING - 2

Question 1

intrinsic enzyme activity or associates directly with an enzyme

Answer 1

cytosolic domain

Question 2

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

Answer 2

enzyme coupled receptors

Question 3

example of enzyme coupled receptor that are important in cell functions (eg. cell to cell communication, movement, cell division, etc.)

Answer 3

receptor tyrosine kinase

Question 4

classified number of RTK’s and subclasses

Answer 4

60 human RTK, 20 subfamilies

Question 5

how is RTK activated in the cytosolic side

Answer 5

binding of signal protein to the ligand binding domain

Question 6

the binding of the ligand-binding domain causes _______ bringing two cytoplasmic domains together

Answer 6

dimerize

Question 7

example of two cytoplasmic domains coming together due to the activation cause by the ligand-binding domain in the RTK

Answer 7

insulin receptors

Question 8

signal molecule that changes the conformation of protein receptors, activating the kinase domains

Answer 8

epidermal growth factor

Question 9

serve as a switch to trigger the assembly of an intracellular signaling complex

Answer 9

receptor phosphorylation

Question 10

families of monomeric GTPases; relays the signals from cell-surface receptors

Answer 10

Ras superfamily

Question 11

coordinately spreads the signal along several distinct downstream signaling pathways

Answer 11

signaling hub

Question 12

types of Ras proteins on humans

Answer 12

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

Question 13

required when RTK signals the nucleus to stimulate cell proliferation or differentiation

Answer 13

Ras proteins in humans

Question 14

two classes of signaling protein that are regulated by Ras proteins

Answer 14

Ras guanine nucleotide exchange factors(Ras-GEF)
Ras GTPase-activating proteins (Ras-GAP)

Question 15

dissociation of GTP and the uptake of GDP activates the Ras

Answer 15

Ras guanine nucleotide exchange factors(Ras-GEF)

Question 16

the hydrolysis of GTP inactivates the Ras

Answer 16

Ras GTPase-activating proteins (Ras-GAP)

Question 17

type of Ras-GEF that mediates the activation of Ras protein through RTK

Answer 17

sons-of-sevenless

Question 18

signaling molecule that promotes Ras activation; required for the formation of photoreceptor cell 7

Answer 18

sevenless

Question 19

relays the signal sent by the activated Ras protein downstream by phosphorylation; mediates different responses inside the same cell

Answer 19

mitogen activated protein kinase module(MAP kinase module)

Question 20

three components of MAP kinase module

Answer 20

MAPK (Erk), MAPKK (Mek), MAPKKK (Raf)

Question 21

MAP kinase module that enters the nucleus; phosphorylates transcription regulatory complexes

Answer 21

MAPK (Erk)

Question 22

conveys the signal from the cell surface towards the nucleus and alters the pattern of gene expression

Answer 22

Ras-MAP kinase-signaling pathway

Question 23

prevents cross talks in between parallel MAP kinase modules

Answer 23

scaffold proteins

Question 24

proteins that responds to different kinds of cell stresses (UV, heat shock, osmotic stress)

Answer 24

JNK and p38 protein

Question 25

regulates both the actin and microtubules that control the cell shape, polarity, motility, and adhesion; activated by GEF's and disabled by GAP's

Answer 25

Rho family monomeric GTPases

Question 26

surface of motor neuron that guides the migrating tip of the axon (growth cone) to its muscle target; Eph family of RTK's

Answer 26

ephrin family

Question 27

activates RhoA (RhoA-GTP); activated by phosphorylation from RTK

Answer 27

ephexin

Question 28

controls gene expression of Tim and Per gene

Answer 28

circadian rhythm

Question 29

controls cell face choices and regulates the pattern formation and continued renewal of the tissues; uses wildly in animal development

Answer 29

Notch receptor protein

Question 30

lateral inhibition or contact dependent cell action; binds to notch receptor proteins

Answer 30

delta

Question 31

single pass transmembrane proteins that requires proteolytic processing to funciton

Answer 31

notch proteins

Question 32

ACTIVATION OF NOTCH PROTEIN: Overview

Answer 32

- delta binds to the notch receptor proteins - the plasma membrane bound proteases cleaves of the cytoplasmic tail of notch - the cleaved off tail translocate to the nucleus to activate the transcription of notch response genes [the cleaving of the tail converts it from being a transcriptional receptor to a transcriptional activator]

Question 33

three steps of notch receptor proteolytic cleavage

Answer 33

1st - biosynthesis 2nd - binding of delta 3rd - cutting of the cytoplasmic tail

Question 34

the cleaved tail of the notch genes

Answer 34

y-secretase

Question 35

signal molecules that act as local mediator and morphogens

Answer 35

Wnt proteins

Question 36

coordinates the polarization of cells in the plane of a developing epithelium

Answer 36

planar polarity pathway

Question 37

regulates the proteolysis of the malfunctional protein β-catenin

Answer 37

Wnt-β-catenin pathway

Question 38

phosphorylates the β-catenin

Answer 38

casein kinase 1 (CK1) and glycogen synthase kinase 3 (GSK3)

Question 39

holds the casein β-catenin protein complex altogether

Answer 39

axin and Adenomatous polyposis coli (APC)

Question 40

Wnt/β-catenin pathway: OVERVIEW

Answer 40

- wnt binds to the frizzled protein and its co-receptor, LDL receptor - the activated receptor complex of frizzled and LDL recruits dishevelled scaffold proteins - the dishevelled scaffold proteins promotes the phosphorylation of LDL receptor using CK1 and GSK3 - axin is brought to the receptor complex, and is inactivated - this disrupts the degradation complex of β-catenin - the pattern of gene transcription is altered [from signal repression to transcriptional activation]

Question 41

an important regulator of cell growth and proliferation

Answer 41

Myc

Question 42

inhibits the proteins ability to bind β-catenin, causing β-catenin to accumulate in the nucleus causing the transcription of c-Myc and other Wnt target genes

Answer 42

Wnc/β-catenin pathway

Question 43

secreted signal molecules and acts as local mediators and morphogens (e.g. Wnt proteins)

Answer 43

hedgehog proteins

Question 44

genes that encode hedgehog proteins

Answer 44

sonic, desert, and indian hedgehog

Question 45

hedgehog proteins are mediated by a latent transcription regulator called; absence of hedgehog proteins causes this regulator to be broken down to fragments, silencing hedgehog proteins

Answer 45

Cubitus interruptus (Ci)

Question 46

keeps the unprocessed Ci out of the nucleus

Answer 46

fused and costal 2 scaffold protein

Question 47

three transmembrane proteins that bind the hedgehog protein

Answer 47

patched, iHog, smoothened

Question 48

recruits the protein complex Ci, fused and, costal 2

Answer 48

smoothened

Question 49

induces endocytosis and degradation; inhibits the activity of patched

Answer 49

binding of hedghog to iHog and patched

Question 50

inhibits hedgehog signaling; negative feedback

Answer 50

genes for patched

Question 51

recognize pathogens and activate this pathway in triggering innate immune responses

Answer 51

Toll receptors in Drosophila; Toll-like receptors invertebrates

Question 52

they trigger multiprotein ubiquitylation and phosphorylation cascade that releases NFKB from an inhibitory protein complex when activated

Answer 52

tumor necrosis factor (TNF ) and interleukin-1 (IL1)

Question 53

inhibitory protein; bind tightly to the dimers and hold them in an inactive state within the cytoplasm of unstimulated cells

Answer 53

IκB

Question 54

translocate to the nucleus and turn on the transcription of genes that participate in inflammatory and innate immune responses

Answer 54

RelA, RelB, c-Rel, NFKB1, and NFKB2

Question 55

types of IκB

Answer 55

IκB α, β, and ε

Question 56

activates the gene that encodes IκBα

Answer 56

NFKB

Question 57

inactivates NFKB proteins; negative feedback inhibition

Answer 57

IκBα

Question 58

negative feedback produces two types of NFκB responses; induce different patterns of gene expression

Answer 58

TNFα-induced responses

Question 59

hydrophobic signal molecules that diffuse directly across the plasma membrane and bind to intracellular receptors (transcription regulators); serves both as intracellular receptors and as intracellular effectors

Answer 59

nuclear receptor superfamily

Question 60

nuclear receptor superfamily with no known ligand

Answer 60

orphan nuclear receptors

Question 61

bind to specific DNA sequences adjacent to the genes that the ligand regulates

Answer 61

nuclear receptors

Question 62

alters the conformation of the receptor protein; causing the inhibitory complex to dissociate; bind coactivator proteins that stimulate gene transcription

Answer 62

ligand binding

Question 63

internal oscillators that control diurnal rhythms; enables an organism to anticipate the regular daily changes in its environment and take appropriate action in advance

Answer 63

circadian clocks

Question 64

controls our diurnal cycles of sleeping and waking, body temperature, and hormone release; found in the suprachiasmatic nucleus of the hypothalamus

Answer 64

SCN cells

Question 65

forms a heterodimer → dissociates and transported into the nucleus; gene products switches off the transcription of their own genes

Answer 65

Tim (timeless) and Per (period) genes

Question 66

cell-surface receptors in plants:

Answer 66

receptor serine/threonine kinases and leucine-rich repeat (LRR) receptor kinases

Question 67

regulate growth and differentiation of plants

Answer 67

brassinosteroids

Question 68

small gas molecule that promote fruit ripening, leaf abscission, and plant senescence; stress signal in response to wounding, infection, flooding, so on.

Answer 68

ethylene

Question 69

located in the endoplasmic reticulum; dimeric, multipass transmembrane proteins

Answer 69

ethylene receptors

Question 70

stimulates the ubiquitylation and degradation in proteasomes of nuclear transcription regulator EIN3; copper-containing ethylene binding domain

Answer 70

CTR1

Question 71

initiation and positioning and helps plants flower and bear fruit; signals the plant to grow toward light, grow upward rather than branch out, and grow roots downward

Answer 71

auxin (indole-3-acetic acid)

Question 72

transport systems of auxin

Answer 72

influx transporter proteins and efflux transporter proteins

Question 73

light sensitive proteins; covalently attached light absorbing chromophore, which changes its shape in response to light and then induces change in the protein’s conformation

Answer 73

photoproteins

Question 74

activated by red light and inactivates in far-red light; translocate into the nucleus and activates transcription regulator

Answer 74

phytochromes

Question 75

tendency of plants to grow toward light (phototrophism) are caused by

Answer 75

phototropin

Question 76

flavoproteins; sensitive to blue light; involved in the repair of ultraviolet induced DNA damage

Answer 76

cryptochromes