Capping the 5ˊ end of eukaryotic pre-mRNA

HO HO 9 Guanine monophos- o The 5’ (y) phosphate of the 3' phate is joined to the first nucleotide is removed. 5’ mRNA end by a 5, 3, S'CH2 0 5’-to- 5' triphosphate /,/ 0- b linkage. Additional mRNA ,x” | 7 | a nucleotide methyla- 5’//’ 0: 'I’“0' '0“ r=° 0 tion also occurs. \ o 0 NHZ H l | B B ‘\ o= r—o- 'O— II’=O —>5'-to- 5' l triphosphate l‘ B 5' (i) a cl) 7 linkage \ _ - __ _ ‘ ase at _ P—o- O P—o \mRNA end CI) ‘l 2 o The 3! and B phosphates are removed from guanine triphosphate. \ l \ \ OH 0 0' C—0 0 0' \ \ / \ / \ P Additional / H3 P RNA - / \\ . / \\ polymerase II - 0 o methylatlon 0 0 .. 0 \CH2 of nucleotides 0 \CH2 OH o\P/cr OH oP/o' \ 0/ \\o 0/ \0 5 . U!