Other Notes Currently available only in Europe. Application Guanosine is a purine nucleoside that upon sequential phosphoylation (kinases) forms GTP which is used by RNA polymerases to synthesis RNA(s). GTP is also important in a wide range of GTPase-dependent cell signaling processes. Guanosine is used in selective matricies such a guanosine gels (G-gels) for use in capillary electrophoresis chiral selection and other applications.