S-adenosyl-L-methionine-dependent 2'-O-ribose methyltransferase that catalyzes the formation of 2'-O-methylguanosine at position 1370 (Gm1370) in the 16S mitochondrial large subunit ribosomal RNA (mtLSU rRNA), a conserved modification in the peptidyl transferase domain of the mtLSU rRNA. guanosine(1370) in 16S rRNA + S-adenosyl-L-methionine = 2'-O-methylguanosine(1370) in 16S rRNA + H(+) + S-adenosyl-L-homocysteine Expressed at same level in normal liver and hepatocarcinoma. Belongs to the class IV-like SAM-binding methyltransferase superfamily. RNA methyltransferase TrmH family.