Releases mononucleotides from RNA in the order of 3'-GMP, 3'-AMP, and 3'-pyrimidine nucleotides. The base specificities of 2 base recognition sites, the B1 site (for the base at 5'-side of scissile phosphodiester bond) and the B2 site (for the base at 3'-side of the scissile bond) are A, G, U > C and A = G > C > U, respectively. Endonucleolytic cleavage to 5'-phosphomonoester. Belongs to the RNase T2 family.