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M2M > Cell signaling > Flashcards

Cell signaling Flashcards

1
Q

Agonist

A

a chemical that binds to a receptor and activates the receptor to produce a biological response

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2
Q

Antagonist

A

a type of receptor ligand or drug that blocks or dampens a biological response by binding to and blocking a receptor rather than activating it like an agonist

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3
Q

Autocrine

A

a form of cell signaling in which a cell secretes a hormone or chemical messenger (called the autocrine agent) that binds to autocrine receptors on that same cell, leading to changes in the cell

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4
Q

Paracrine signaling

A

local, close

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5
Q

Endocrine signaling

A

Long distance signaling, uses circulatory system

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6
Q

cAMP

A

is a second messenger, used for intracellular signal transduction, such as transferring into cells the effects of hormones like glucagon and adrenaline, which cannot pass through the plasma membrane

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7
Q

Dephosphorylation

A

the removal of a phosphate (PO43−) group from an organic compound by hydrolysis

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8
Q

Effector

A

usually a small molecule that selectively binds to a protein and regulates its biological activity. In this manner, effector molecules act as ligands that can increase or decrease enzyme activity, gene expression, or cell signalling.

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9
Q

Heterotimeric G protein

A

the molecular switches that turn on intracellular signalling cascades in response to the activation of G-protein-coupled receptors (GPCRs) by extracellular stimuli. Therefore, G proteins have a crucial role in defining the specificity and temporal characteristics of the cellular response.

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10
Q

What are some qualities in cell signaling?

A
  • short or long distance
  • immediate or longer (change in gene expression)
  • public or private
  • to the cell or to other cells
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11
Q

What mechanisms can terminate the intracellular signaling pathway once the concentration of the external signal decreases?

A
  • degradation of the second messenger
  • desensitization of receptors
  • deactivation of a signal transduction protein
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12
Q

Interferons are “pleiotropic” cytokines (pro-inflammatory in some contexts and anti-inflammatory in others). Explain this.

A

the response of a cell or tissue to interferons depends on the gene expression of that cell or tissue, specifically the collection of receptors, signal transduction proteins, and effectors expressed

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13
Q

G- protein

A

a family of proteins that act as molecular switches inside cells, and are involved in transmitting signals from a variety of stimuli outside a cell to its interior.

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14
Q

Paracrine

A

relating to or denoting a hormone that has effect only in the vicinity of the gland secreting it.

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15
Q

Phosphorylation

A

ATP is also synthesized by substrate-level phosphorylation during glycolysis.

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16
Q

Protein kinase

A

kinase enzyme that modifies other proteins by chemically adding phosphate groups to them (phosphorylation). Phosphorylation usually results in a functional change of the target protein (substrate) by changing enzyme activity, cellular location, or association with other proteins.

17
Q

Protein phosphatase

A

an enzyme that removes a phosphate group from a protein

18
Q

cGMP

A

a cyclic nucleotide derived from guanosine triphosphate (GTP). cGMP acts as a second messenger much like cyclic AMP.

19
Q

Threonine kinase

A

a kinase enzyme that phosphorylates the OH group of serine or threonine (which have similar sidechains).

20
Q

Transduction

A

the process by which foreign DNA is introduced into a cell by a virus or viral vector. An example is the viral transfer of DNA from one bacterium to another.

21
Q

Tyrosine kinase

A

an enzyme that can transfer a phosphate group from ATP to a protein in a cell. It functions as an “on” or “off” switch in many cellular functions. Tyrosine kinases are a subclass of protein kinase. The phosphate group is attached to the amino acid tyrosine on the protein.

22
Q

What are the four steps of signaling systems?

A
  • an external stimulus activates a receptor
  • the receptor activates cytoplasmic transducers, amplifying the signal
  • transducers activate effectors, changing the biochemistry of the cell
  • transducers and/or effectors feed back to higher levels of the pathway to modulate, usually attenuate or shape the response
23
Q

What are the key physical features of cyclic nucleotides and how are they generate?

A
  • water soluble and highly mobile (act globally)

- generated by specific cyclases catalyzing ATP to form cAMP (or GTP to cGTP)

24
Q

How are cyclic nucleotides removed and what do they target?

A
  • hydrolysis by phosphodiesterase to AMP and GMP
  • targets cyclic nucleotide-activated protein kinases (PKA, PKG), cyclic nucleotide-gated ion channels, and (for cAMP) one GEF
25
Q

What are key physical properties of lipid secondary messengers?

A
  • some are membrane-bound and work locally
  • some are water soluble and diffuse in cytoplasm
  • some diffuse out of cells and activate seven-helix receptors (arachidonic acid, prostaglandins, leukotrienes)
26
Q

How are lipid secondary messengers removed?

A

most are degraded enzymatically

27
Q

What are the targets of lipid secondary messengers?

A

PKC (DAG, arachidonic acid), Ca-release channels, seven helix receptors (prostaglandins, leukotrienes), pH-domain kinases

28
Q

What are calcium’s key physical properties?

A
  • water-soluble and poorly mobile in cytoplasm (act locally)

- binding to calmodulin allows greater mobility

29
Q

How is calcium allowed in to the cell and removed?

A
  • released into cytoplasm by voltage-gated Ca channels in plasma membrane or Ca-release channels in ER
  • pumped out of the cytoplasm into the ER and out of the cell by P-type pumps (Ca-ATPase)
30
Q

What controls calcium bursts or waves?

A
  • concentration of both IP3 and cytoplasmic Ca2+ control the opening of Ca-relesae channels
  • When both are low, channels are closed
  • With µM concentrations of IP3 and a resting concentration of Ca2+, the release channels open
  • once Ca2+ is µM, inhibits type I release channels
31
Q

Targets of Ca2+?

A
  • calmodulin (which binds and activates many downstream effector proteins)
  • troponin C, PKC, calpaan, gelsolin

M2M (41 decks)

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