C-methyltransferase activity rRNA (cytosine-C5-)-methyltransferase activity Reactome:R-HSA-6793057 molecular_function rRNA m5C967 methyltransferase activity rRNA (cytosine-C5-967)-methyltransferase activity Catalysis of the transfer of a methyl group from S-adenosyl-L-methionine to cytosine to form 5-methylcytosine in small subunit ribosomal RNA. GO:0009383 Reactome:R-HSA-6790944 rRNA (cytosine) methyltransferase activity