Cglucosylations

C-glycosylation is a type of post-translational modification where a sugar moiety is attached to a protein via a carbon-carbon bond, rather than the more common carbon-oxygen or carbon-nitrogen bonds. This process differs significantly from O-glycosylation and N-glycosylation in terms of the bond formed and the enzymes involved. The term "C-glycosylation" specifically refers to the attachment of a sugar where the anomeric carbon of the sugar forms a direct bond with a carbon atom on an amino acid side chain.

In mammals, C-glycosylation is a relatively rare modification compared to O- or N-glycosylation. The most well-studied example involves the attachment of mannose to the C2 position of a tryptophan residue, forming a C-mannosyltryptophan linkage. This modification has been observed in several important proteins, including certain immunoglobulins, gonadotropins, and complement factors. The enzymes responsible for C-glycosylation are distinct from those involved in O- and N-glycosylation and are generally less well-characterized.

The biological significance of C-glycosylation is still an active area of research. However, it is believed to play roles in protein folding, stability, receptor binding, and immune responses. The stable nature of the C-C bond may confer increased resistance to enzymatic degradation compared to other glycosylation types. Studies have also suggested that C-glycosylation can influence the three-dimensional structure and overall function of the modified proteins. The discovery and ongoing investigation of C-glycosylation continue to expand our understanding of the diverse ways proteins are modified in biological systems.