TGFB Signalling Pathways Flashcards

1
Q

What is TGFB?

A

Transforming growth factor beta 1: Is a prototype of a family of signalling molecules that includes important cellular transformations or differentiations.

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2
Q

How are TGFB discovered?

A

Studies of development.

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3
Q

What do TGFB affect?

A

Cell proliferation, differentiation and migration.

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4
Q

What happens if the TGFB has a mutation?

A

They will have strong, specific effects on embryonic development.

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5
Q

What was TGFB first classified as? What is it classified as now?

A

An oncogene.

A tumor suppressor.

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6
Q

Oncogenes vs tumor suppressor?

A

Oncogenes: Cause cancer if they are permanently turned on.

Tumor Suppressor: Cause cancer if they are permanently turned off.

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7
Q

What are the three families of the TGFB?

A
  1. TGFB Family
  2. Activin Family
  3. Bone morphogenic protein
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8
Q

What does the TGFB family do?

A

Inhibit cell growth/division, induce formation of extracellular matrix.

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9
Q

What does the activin family do?

A

Early embryonic development.

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10
Q

What does activin itself stimulate? Inhibin?

A

Stimulate pituitary to release FSH, a key step in ovulation.

Inhibin prevents FSH release.

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11
Q

What does bone morphogenic protein (BMP)?

A

Involved in many developmental processes.

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12
Q

What are TGFB family ligands typically?

A

Dimers.

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13
Q

What are the TGFB dimers usually made of and how are they held together?

A

They are dimers made of identical subunits, held together by three disulfide bonds.

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14
Q

What are the three disulfide bonds of the TGFB dimers made of?

A

Three cysteine residues called the cystine knot.

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15
Q

What are inhibit and some of the BMPs classified as?

A

Heterodimeric (two different polypeptides).

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16
Q

What are the two receptors of the TGFB family ligands?

A

They are also dimers, and type I and type II.

17
Q

What makes each type I and type II receptor?

A

Each as an extracellular domain, a single transmembrane domain, and a cytoplasmic domain.

18
Q

What do these receptors resemble?

A

Growth factor receptors.

19
Q

What are the two key differences between growth factor receptor and TGFB receptors?

A
  1. Productive ligand binding requires both a Type I and a Type II dimer to come together. A assembled receptor is a tetramer.
  2. The cytoplasmic domains of the receptors contain a Ser/Thr-specific rather than Try-specific protein kinase.
20
Q

What is the difference between the amino acid sequences of type I and type II receptors?

A

The type I receptors have an extra Gly-Ser rich region (the GS domain) just inside the membrane.
The type II receptors are a little longer overall.

21
Q

What are the three ways of ligand binding?

A
  1. Ligand binds to type I dimer then dimerization of type II.
  2. Ligand binds to type II dimer the dimerization of type I.
  3. Type-I, Type II receptor complex forms first and then the ligand binds.
22
Q

Which type of receptors use which ligand binding methods?

A
  1. TGFB
  2. BMP
  3. TGFB