label: a guanosine in miRNA + S-adenosyl-L-methionine <=> an N(7)-methylguanosine in miRNA + S-adenosyl-L-homocysteine
label_lc: a guanosine in mirna + s-adenosyl-l-methionine <=> an n(7)-methylguanosine in mirna + s-adenosyl-l-homocysteine