Brent Cornell

      
If a protein is labelled to enable detection, its subsequent movements can be tracked to gain information about its function

• Tracking protein locations can provide information about cellular and subcellular targets for protein activity
• Tracking protein interactions can provide information about reaction pathways with which the protein is involved

Proteins can be tracked by tagging with a fluorescent molecule to enable detection with appropriate imaging devices

• Consideration must be given as to whether forming a fluorescent complex will impair its ability to interact with targets

Alternatively, proteins can be tracked by incorporating radioactively labelled amino acids into its structure

• This is called a pulse-chase experiment, as the protein is radiolabelled (‘pulse’) to enable its temporary detection (‘chase’)

      
Transferrins are protein molecules that transport iron within the blood plasma

• Transferrin facilitates iron uptake into target cells by binding to specific transferrin receptors, which mediate endocytosis

The expression of transferrin receptors is significantly upregulated in tumour cells (i.e. they have a lot more of them)

• This means that transferrins will bind more frequently to tumour cells as they have more transferrin receptors
• If transferrin is linked to a luminescent probe, tumour cells will therefore show greater luminescence

Transferrin Receptor Upregulation in Tumour Cells

Tumour Tracking

Because tumour cells will luminesce more brightly, transferrin-linked luminescent probes can be used to locate tumours

• This can be useful in determining the rates of cancer progression in test animals – which is helpful in developing treatments
• It can also be used to determine the extent of spread of a cancer should it metastasise to another tissue

Locating Tumours with Luminescent Probes