Bovin beta-1,4-galactosyltransferase 1 (Y289L) (Bovin B4GALT1 (Y289L)) is a mutated form of bovine-derived galactosyltransferase with a mutation at the Y289L genetic site. Bovin beta-1,4-galactosyltransferase 1 can label O-GlcNAcylated proteins with an N-azidoacetylgalactosamine (GalNAz) group. This labeling method allows for the specific, unbiased, and global labeling of O-GlcNAcylated proteins. After labeling, the appended azide group can react with a wide variety of alkyne-modified chemical probes, facilitating multiple downstream analyses^[1].