S-adenosyl-L-methionine-dependent methyltransferase that specifically methylates the N(7) position of a guanine in 18S rRNA. Important for biogenesis end export of the 40S ribosomal subunit independent on its methyltransferase activity (By similarity). S-adenosyl-L-methionine-dependent methyltransferase that specifically methylates the N(7) position of a guanine in 18S rRNA. Requires the methyltransferase adapter protein TRM112 for full rRNA methyltransferase activity. Involved in the pre-rRNA processing steps leading to small-subunit rRNA production independently of its RNA-modifying catalytic activity. Important for biogenesis end export of the 40S ribosomal subunit independent on its methyltransferase activity. a guanosine in 18S rRNA + S-adenosyl-L-methionine = an N(7)-methylguanosine in 18S rRNA + S-adenosyl-L-homocysteine Belongs to the class I-like SAM-binding methyltransferase superfamily. BUD23/WBSCR22 family.