a guanosine in 18S rRNA + S-adenosyl-L-methionine => an N(7)-methylguanosine in 18S rRNA + S-adenosyl-L-homocysteine
a guanosine in 18s rrna + s-adenosyl-l-methionine => an n(7)-methylguanosine in 18s rrna + s-adenosyl-l-homocysteine