Fig. 6.

Model depicting the ability of the elongated, tilted CD22 structure to form nanoclusters on the surface of B cells. Binding to Sia-terminated glycans in cis (blue surface) and trans (red surface) is proposed to be mediated by the flexibility of branched complex glycans (inset) and the local micro-environment. The CD22 ECD EM envelope is shown as gray surface, fitted with the crystal structure of CD22_20–330,5A. N-linked glycans modeled at all CD22_20–330,5A-predicted sites are shown as blue surfaces. BCRs (sky blue and cyan) (PDB IDs: 1HZH and 3KH0)^{68, 69} are shown binding to self-antigens (pink) (PDB ID:4ZXB)⁷⁰ on an interacting cell (salmon surface). Blue arrow represents BCR activation, whereas red dashed line represents CD22-mediated BCR inhibition. Engagement of CD22 with trans glycans (red) promotes recruitment of CD22 nanoclusters to the immune synapse resulting in B-cell inhibition