Tracking Experiments

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•  Tracking experiments are used to gain information about the localization and interaction of a desired protein

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’)

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•  Tracking tumour cells using transferrin linked to luminescent probes

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

tumor tracking