Lecture 28 Flashcards
1
Q
enzyme-coupled receptors are
A
- transmembrane proteins that act as enzymes or associate with another protein that acts as an enzyme
- response are usually slow and usually result in gene expression
2
Q
What is the largest class of enzyme couples receptors
A
- receptor tyrosin kinsases (RTKs)
- they are single pass transmembrane proteins
- the receptors often form dimers upon binding with extracellular signalling molecules
- tyrosine residues on cytoplasmic tails are phosphorylated which serve as docking sites for other proteins
3
Q
RTKs are ______ transmembrane proteins
A
single pass
4
Q
interaction domain
A
- recognize phosphorylated tyrosine on the tail
5
Q
Termination of the signal
A
- protein phosphatases dephosphorylate the tyrosines
- others are endocytosed and destroyed by the lysosomes
6
Q
RTKs activate
A
- the monomeric GTPases Ras
- Ras-GEF : encourages Ras to exchange GDP for GTP which activates Was
- Ras-GAP: which inactivates Was by promoting GTP hydrolysis
7
Q
Example of phosphorylation cascade
A
- Mitogen activated protein kinase (MAP kinase) pathway
8
Q
Mitogen is
A
mitogen is an extracellular signalling molecules that stimulates cell proliferation
9
Q
what happens when cancers involve mutation in RAS
A
- it inactivates GTPases
- this prevents cell from being turned off and results in uncontrolled proliferation
10
Q
oncogene
A
- a gene that when activated can potentially make a cell cancerous
11
Q
A