Inhibits protein synthesis by binding to L6 protein of 50S ribosomal subunit. Antibacterial. Antibiotic complex consists of three closely related components, gentamicins C1, C2, C1a, and also gentamicin A which differs from the other members of the complex but is similar to Kanamycin C. Gentamicin C1: R1=R2=CH3 Gentamicin C2: R1=CH3; R2=H Gentamicin C1A: R1=R2=H