Ribostamycin:4-(gamma-L-glutamylamino)-(S)-2-hydroxybutanoyl-(BtrI acyl-carrier protein) 4-(gamma-L-glutamylamino)-(S)-2-hydroxybutanoate transferase (EC 2.3.2.19 btrH (gene)) is an enzyme with system name ribostamycin:4-(gamma-L-glutamylamino)-(S)-2-hydroxybutanoyl-(BtrI acyl-carrier protein) 4-(gamma-L-glutamylamino)-(S)-2-hydroxybutanoate transferase.