Extracellular antibodies are ideal research tools for cell-surface proteins.

No permeabilization/fixation because using extracellular antibodies allows you to work with live cells!

Benefits of live cell imaging:
✓ Monitor cell movement
✓ Study protein transport across the cell
✓ Investigate protein internalization

Neurotrophins, like many growth factors, are expressed as precursor proteins which are then truncated and further modified to yield the mature form. The presence of highly conserved sequences in the prodomains of different neurotrophins made it clear that the prodomain must have some biological role and is not solely present as a protein folding chaperone. Proneurotrophins mediate their signaling by binding to p75^NTR and Sortilin receptors.