GPCR (session 9) Flashcards
What is a G Protein coupled receptor?
GPCR is an integral transmembrane protein with seven helices, involved in signal transduction across the fell membrane
What happens when GTP binds to a G-Protein?
The G-protein becomes active, enabling signal transduction.
What is the state of a G-Protein when bound to GDP?
The G-Protein is inactive
How does GTP act as an energy currency in GPCR signalling?
GTP activates proteins by binding to them, it is hydrolysed to GDP to inactivate the proteins.
Outline the main steps of the GPCR pathway
- Ligand bunds to GPCR
- GPCR changes confirmation
- G-protein replaces GDP with GTP
- Active G-protein subunits transmit signals
- GTP is hydrolysed back to GDP, resetting the pathway
What secondary messenger is involved in the adrenaline pathway?
cAMP (cyclic AMP)
Which subunit of the G-protein activates ion channels?
The beta-gamma subunits
What is the key difference between normal and cancerous cells in GPCR studies?
Cancerous cells have mutated membrane proteins due to DNA changes
How dies the immune system recognise and fight cancer cells?
By detecting surface markers as self, mutated, or foreign. Mutated proteins triggers apoptosis, while foreign markers initiate an immune response.
Why can tumour markers evade immune detection?
They may appear normal, overproduce proteins, or re-activate embryonic proteins
What does elevated PSA indicate?
Higher risk of prostate cancer
What is the role of HPV in cervical cancer?
HPV-16 is a leading cause, and vaccination prevents related cancers
How are antibodies used to detect cancer makers?
Specific antibodies bind to antigens on cancer cells, aiding in detection.
What is the principle behind the immunoprecipitation test?
Antigens bind to multiple antigen molecules, forming visible aggregates
What happens if antigen levels are very low in the blood?
Aggregates may not form or be too small to detect
How is the presence of antigens identified in immunoprecipitation?
By observing the size of the aggregate formed
