MR glycans contribute 15 kDa to the relative molecular mass of MR. The glycosylation profile of
SB203580 MR suggested that the majority of N-glycans contain sialic acids, mainly mono- and di-sialylated structures, although there was also a significant proportion of neutral sugar glycans present. Terminal sialic acids are required for mannose recognition mediated by MR-CTLDs. They also modulate the tendency of MR to self-associate and interact with sulphated sugar ligands [17]. Sialytransferases/sialydases are involved in the modulation of oligosaccharide sialylation on the cell surface that occurs upon activation of some cell types. Therefore, the alteration of sialylation status of MR could provide a means for
cells to modulate MR-related patho-physiological functions in vivo. For instance, in tumorgenesis, sialylated MR might be involved in the metastasis of L-selectin-expressing malignant cells and thus assist the spread of L-selectin positive tumor cells [12]. Many other macrophage glycoproteins, such as ferritin, scavenger receptor class A, HLA-DR molecules and macrosialin have also been shown to alter their glycan processing in response to various stimuli, such as Th1 cytokines (INFγ) and Th2 cytokine (IL-4) or phagocytic stimuli [24], [25] and [26].
