Lecture 2-3 Flashcards
Define Kinase
An enzyme that phosphorylates something (ATP)
What does the type of sensory mechanism used depend on?
the type of environmental signal i.e. simple or complex system
What is a signal introduction system
The external signal is transmitted from a surface protein to the interior of the cell
What are the two components of the sensor regulator system
- A sensor kinase
2. The response regulator proteins
What do sensors do?
Enzymes that use ATP to add a phosphate group to a specific histidine amino acid of a protein
True or false: The C terminus of sensors proteins has the same sequence for many different sensor proteins
True `
Where do sensor proteins contain their histidine
in the C terminal region at the transmitter domain ( T terminus is front, C is back)
Describe a typical sensor protein
2 sections that are hydrophobic enough to be in the membrane (transmits signals to cytoplasmic domain) and are separated by a hydrophilic secion that can function as a receptor
What are response regulators
- A two part cytoplasmic protein:(Receiver + Regulator)
- Transcriptional activator activity
- Phosphatease activity to reset system
Explain the receiver domain in a response regulator
N terminal ~100 amino acids long contains a conserved aspartate residue - It can be phosphorylated by the sensor protein
Explain the regulator domain as part of a response regulator
C terminal end of the protein is often a transcriptional activator or interacts with another peotein
Explain transcriptional activator activity as part of a response regulator
- DNA binding site beside promoter
- Binds when sensor phsphorylates N terminal end in response to a signal
- Works with global requlatory mechanisms which make alternative sigma proteins for RNA polymerase
Explain what phosphatase activity does in a response regulator
ITs required to reset the system
- Usually part of regulator protein
- Slower then the phosphorylation reaction
- acts as a feedback loop
