Trinucleotide cap analogs with N6-adenosine modifications: interaction partners in HEK293F cell line

A series of trinucleotide cap analogs functionalized with an amine-terminated linker at the guanosine ribose and immobilized on BrCN-activated Sepharose was prepared. These affinity resins AR-1 (Am), AR-2 (m6Am), and AR-3 (Bn6Am) were incubated with HEK293F cell extract in the presence of GTP to limit non-specific interactions. The pulled-down proteins were eluted with the corresponding trinucleotide cap analog (m7GpppAmpG for AR-1, m7Gpppm6AmpG for AR-2, and m7GpppBn6AmpG for AR-3), digested with trypsin, labeled with isobaric tags (TMT), and analyzed by shotgun proteomics. This experiment was performed in order to assess binding preferences of proteins to the resins AR-1, AR-2, and AR-3.