3.4. Cellular Communication Intro To Signalling

Question 1

Autocrine

Answer 1

Signaling molecules secreted by cell and bind to cell surface receptors on same cells that produce them

Question 2

Paracrine

Answer 2

1. Signaling molecules released into the extra cellular space & act locally on neighbouring cells
   - > signaling molecules rapidly degraded

Question 3

Contact-dependent signaling/

Cell-to-cell signaling

Answer 3

Cell needs to be in direct membrane-membrane contact

Question 4

Synaptic signaling (neuronal)

Answer 4

1. Nerve cells transmit signals

2. Named for synapse -> junction between two nerve cells or nerve & motor cell where signal transmission occurs

Question 5

Endocrine

Answer 5

Depends on endocrine cells

-> secrete hormones into bloodstream => act on distinct target cells in the body

Question 6

Intracellular receptor

Answer 6

Hydrophobic signaling- hydrophobic ligand

Question 7

Transcription factor

Answer 7

1. Formed by ligand & receptor

2. Results in production of specific proteins

Question 8

HRE

Answer 8

Hormone response element

Question 9

Membrane receptors

Answer 9

Hydrophilic signaling- hydrophilic ligand

• final result
  1. Proteins with altered functions
  2. Transcription factors activated => production of new proteins

Question 10

Ligand

Answer 10

1. Extra cellular signaling molecules
2. Bind to specific receptors
3. Also known as:
   First messenger, hormones
   E.g. chem ok ones, cytokines, growth factors, hormones

Question 11

Membrane receptors

Answer 11

Proteins present in membrane that bind to specific ligands

Question 12

Adaptors

Answer 12

Relatively small proteins usually with no more than two or three domains whose function is to link two proteins together

Question 13

G proteins

Answer 13

1. Bind GTP to GDP
2. GDP bound => inactive
3. Activated by exchange of GDP to GTP
   - > when GTP bound active

Question 14

Intrinsic GTPase activity

Answer 14

Convert GTP back to GDP by removing terminal

Question 15

Heterotrimeric

Answer 15

Alpha unit binds GTP/ GDP

e.g. Gs, Gq

Question 16

Small monomeric

Answer 16

RAS

Question 17

GPCR

Answer 17

G protein coupled receptor

Question 18

Effector enzymes

Answer 18

Produce second messengers-
Diffusible chemicals
E.g. cAMP, IP3

Question 19

Second messengers

Answer 19

Activate kinases

Question 20

Protein kinases

Answer 20

Add gamma phosphate from ATP to amino acid with OH group

E.g. serine, threonine or tyrosine

Question 21

Scaffold proteins

Answer 21

1. Large proteins able to bind various other proteins to bring them together in a complex
2. Have no enzymatic activity
3. Can be phosphorylated at various sites & thus recruit many different proteins with SH2 domains
4. Axin & APC in Wnt pathway are scaffold proteins

Question 22

Transcription factors

Answer 22

1. Proteins that bind to promoters of genes & either increase or decrease transcription of gene
2. Promoter contains conserved consensus sequence

Question 23

Conserved consensus sequence

Answer 23

1. Binds general transcription factors and other specific sequences which bind specific transcription factors
   E.g. NFxB, AP-1

Question 24

Specific transcription factors

Answer 24

1. Gives specificity to signal

Question 25

Combined response

Answer 25

Occur when genes with promoters with same sequence bind to transcription factors