Ectolysins help the phage gain entry from outside into the bacterial cell. Endolysins help the phage progeny to burst open & exit the bacterial cell. 
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GangaGen has used its proprietary PATP to design novel lysin molecules to target both Gram positive and Gram negative pathogens. The most advanced of these is P128 (Staphtame), an Ectolysin that is active on Staphylococci and progressed to clinical trials in man.