Fig. 7

Bioassay of purified Fc-GLP1 fusion proteins. HEK cells expressing the GLP-1R were used to assess the ability of Fc-GLP1 fusion proteins purified from the spent medium of different CHO cell lines to stimulate cAMP production. a The activity of GLP1, GP-GLP1-NH₂ and GP-GLP1was compared; as expected, amidation did not affect bioactivity while appending the GP dipeptide to its amino-terminus reduced the potency of GLP1-NH₂. b The activity of GLP1 was compared to that of Fc-AP-GLP1 fusion proteins purified from the spent media of WT CHO cells, CHO cells expressing PAM1 and WT CHO cells treated with 10 μM bathocuproine disulfonate to inhibit endogenous PHM throughout the entire collection period. Parallel dose–response curves were observed for all of the peptides and proteins tested; Fc-GLP1 was at least 10,000-fold less active than GLP1. The y-axis shows the TR-FRET signal at 665 nm; the signal obtained by cells in the absence of any added peptide is indicated