Figure 3. Effect of C-terminal amino acids on CPY-catalyzed protein biotinylation.
(A) GST fusion proteins containing each of twenty amino acids at the C-terminus can be biotinylated with CPY. Each GST protein (1 µg) was methyl esterified and incubated with CPY and biocytinamide at 37°C for 30 min. Because of the limited number of samples that can be loaded per gel, these experiments were conducted on two blots that were Western blotted with an anti-biotin antibody and exposed simultaneously.
(B) CPY-mediated biotinylation of naturally occurring proteins. The indicated proteins (1 µg) were methyl esterified and labeled with CPY and biocytinamide. The top band in the myoglobin lane is a contaminant.