Probable S-adenosyl-L-methionine-dependent methyltransferase that mediates mRNA cap2 2'-O-ribose methylation to the 5'-cap structure of mRNAs. May methylate the ribose of the second nucleotide of a m(7)GpppG-capped mRNA (cap0) to produce m(7)GpppRmpNm (cap2) (By similarity). Regulates expression of tracheal genes required for pathfinding on the segmental nerve (PubMed:10068643). a 5'-end (N(7)-methyl 5'-triphosphoguanosine)-(2'-O-methyl-ribonucleoside)-(ribonucleotide) in mRNA + S-adenosyl-L-methionine = a 5'-end (N(7)-methyl 5'-triphosphoguanosine)-(2'-O-methyl-ribonucleoside)-(2'-O-methyl-ribonucleotide) in mRNA + H(+) + S-adenosyl-L-homocysteine Maternally expressed and distributed during the syncytial blastoderm stage. In zygote first detected in mid-embryogenesis in the developing tracheal system and later in the developing gonad. Tracheal expression is highly dynamic. At stage 11, weakly expressed in all tracheal cells. During stages 12 and 13, preferential expression in the leading cells of the ganglionic branch and other growing primary branches. During stages 14 and 15, expression becomes further restricted to just the GB1 terminal cell and other terminal cells. Induced by the branchless FGF pathway in migrating tracheal cells, resulting of the switch from the intersegmental to the segmental nerve. Ganglionic branches migrate normally along the intersegmental nerve, but sporadically fail to switch to the segmental nerve and enter the CNS; they wind up meandering along the ventral epidermis instead.