S-adenosyl-L-methionine-dependent pseudouridine N(1)-methyltransferase that methylates pseudouridine at position 1189 (Psi1189) in 18S rRNA. Involved the biosynthesis of the hypermodified N1-methyl-N3-(3-amino-3-carboxypropyl) pseudouridine (m1acp3-Psi) conserved in eukaryotic 18S rRNA. N1-methylation is independent on acp-modification at the N3-position of U1191. Has also an essential role in 40S ribosomal subunit biogenesis independent on its methyltransferase activity, facilitating the incorporation of ribosomal protein S19 (RPS19A/RPS19B) during the formation of pre-ribosomes. pseudouridine(1191) in yeast 18S rRNA + S-adenosyl-L-methionine = H(+) + N(1)-methylpseudouridine(1191) in yeast 18S rRNA + S-adenosyl-L-homocysteine Homodimer. Interacts with snoRNA U3. Interacts with NOP14 and MPP10. Component of the ribosomal small subunit (SSU) processome composed of at least 40 protein subunits and snoRNA U3. Depletion of EMG1 affects growth and leads to strong ribosome biogenesis defects, with defects in 20S pre-rRNA and mature 18S rRNA species. Belongs to the class IV-like SAM-binding methyltransferase superfamily. RNA methyltransferase NEP1 family.