Most modern vectors contain a variety of convenient cleavage sites that are unique within the vector molecule (so that the vector can only be cleaved at a single site) and are located within a gene (frequently beta-galactosidase) whose inactivation can be used to distinguish recombinant from non-recombinant organisms at a later step in the process.
A maioría dos vectores modernos conteñen unha variedade de sitios de clivaxe convenientes que son únicos dentro da molécula vector (de modo que o vector só pode ser clivado nun só sitio) e están localizados dentro dun xene (frecuentemente o da beta-galactosidase) cuxa inactivación pode utilizarse para distinguir os organismos recombinantes dos non recombinantes nun paso final do proceso.