Alpha-sarcin is specific for purines in both single- and double-stranded RNA. Its toxic action on eukaryotic cells is the result of cleavage of a single phosphodiester bond in the 60S subunit of ribosomes (By similarity). Inhibits both the EFl (elongation factor 1)-dependent binding of aminoacyl-tRNA and the GTP-dependent binding of EF2 (elongation factor 2) to ribosomes (PubMed:2930482). a 28S rRNA containing guanosine-adenosine pair + H2O = an [RNA fragment]-3'-adenosine-3'-phosphate + a 5'-a hydroxy-guanosine-3'-[RNA fragment]. Belongs to the ribonuclease U2 family.