While SNAP-tag®/CLIP-tag™ technologies are complementary to GFP, there are several applications for which SNAP- and CLIP-self-labeling technologies are advantageous.
|Application||SNAP-tag/CLIP-tag||GFP and other fluorescent proteins|
|Time-resolved fluorescence||Fluorescence can be initiated upon addition of label||Color is genetically encoded and always expressed. Also, photoactivatable fluorescent proteins require high-intensity laser light, which may activate undesired cellular pathways (e.g., apoptosis)|
|Pulse-chase analysis||Labeling of newly synthesized proteins can be turned off using available blocking reagents (e.g., SNAP-Cell® Block)||Fluorescence of newly synthesized proteins cannot be quenched to investigate dynamic processes|
|Ability to change colors||A single construct can be used with different dye substrates to label with multiple colors||Requires separate cloning and expression for each color|
|Surface-specific labeling||Can specifically label subpopulation of target protein expressed on cell surface using non-cell permeable substrates||Surface subpopulation cannot be specifically visualized|
|Single molecule detection||Conjugation with high quantum yield and photostable fluorophores||Fluorescent proteins are generally less bright and photobleach quicker than most organic fluorophores|
|Visualizing fixed cells||Resistant to fixation; strong labeling||Labile to fixation; weak labeling|
|Pull-down studies||"Bait" proteins can be covalently captured on BG beads||Requires anti-GFP antibody to non-covalently capture “bait" protein, complicating downstream analysis|
|Live animal imaging||Cell permeable far red dye available, permitting deep tissue visualization||Signal is easily quenched by fixation ( whole-mount specimens or thick sections); Limited spectral flexibility and weaker fluorescence|
SNAP-tag® and SNAP-Cell® are registered trademarks of New England Biolabs, Inc.
CLIP-tag™ is a trademark of New England Biolabs, Inc.