Lecture 8 Signaling Pathways: Objective 1, major morphogenic signal factor families

Question 1

TGF-Beta1

Answer 1

Transforming Growth-beta Family

Disulfide linked dimer
Two 390 amino acid groups
1 proregion and 1 bioactive region

1. proregion is cleaved in two; 2 bioactive regions cleaved
2. all four are secreted
3. bioactive regions form a dimer
4. proregions reassociate with bioactive dimer to form latent form
5. activated by another cleavage, proregions released and bioactive dimer functions as a signaling molecule

Question 2

TGF-beta 1 family: bone morphogenetic proteins

modes of action

Answer 2

often inhibit other processes in the embryo

often act by being inhibited (as in the central nervous system): bind to bioactive dimers and prevent them from binding to receptors

Question 3

Fibroblast Growth Factor Family: means of regulation

Answer 3

modification of interaction with heparan proteoglycans in the receptor complex

regulates at the membrane of responding cell via transmembrane proteins

regulation of various molecules at the transduction machinery

Question 4

Hedgehog Family

Answer 4

related to segment molecule in drosophila

includes: desert, indian, sonic hedgehog

Question 5

Wnt Family

Answer 5

Related to the segment polarity gene in drosophila

often interacts with components of the ECM

Question 6

Receptors with intrinsic protein kinase activity

name some of the families and their attributes

Answer 6

Fibroblast Growth Factors Family: possess a cytoplasmic domain with tyrosine kinase activity

TGF-beta family: cytoplasmic domains which possess threonine/serine kinase activity

Question 7

What kind of receptor molecules are used in embryological development ? no specifics

Answer 7

intracellular receptors
cell surface receptors (protein kinase activity)
secondary messengers