L-homopropargylglycine (Hpg), an alkyne-tagged analog of methionine, has been used to selectively tag newly synthesized mammalian proteins in a method similar to conventional pulse-chase labeling, and labeled proteins were visualized via fluorescence. Protein translation has been implicated in different forms of synaptic plasticity, but direct in situ visualization of new proteins is limited to one or two proteins at a time. Homopropargylglycine is a noncanonical amino acid which can incorporate into proteins followed by chemoselective fluorescence tagging by means of 'click chemistry'. Pulse-chase application of homopropargylglycine allowed visualization of proteins synthesized in two sequential time periods. This technique can be used to detect changes in protein synthesis and to evaluate the fate of proteins synthesized in different cellular compartments [1].

Reference:
[1] Dieterich D C, Hodas J J L, Gouzer G, et al.  In situ visualization and dynamics of newly synthesized proteins in rat hippocampal neurons[J]. Nature neuroscience, 2010, 13(7): 897-905.