**3. C-Mannosylation**

C-mannosylation is different approach from glycosylation, as in this process there is reaction forms carbon-carbon bonds rather than carbon-nitrogen and carbon-oxygen bonds. C-mannosyltransferase is the key enzyme that is involved in the C-mannosylation. This enzyme conjugates the C1 of the mannose to C2 of the indole ring present in the tryptophan residue [7]. Moreover, this enzyme recognizes the specific sequence of Trp-X-X-Trp that further ease the transfer of mannose sugar from dolichol-P-Man to the first Trp residue present in the given sequence [8–10]. In another event of the post translational modification (PTM), the phosphoglycosylation is among the PTM mechanism that is limited to the parasites including Trypanosoma and Leishmania including slime molds. The mechanism is characterized by the conjugation of glycans to the Ser and Thr residues linked by the phosphodiester bonds [11].
