FIG. 4.

Conformational variability of the V1 loop in the context of the gp140 trimer. The structure of V1V2 (positions 126–196) is shown in ribbon and stick representation, while the rest of the trimer is shown in skin representation. Each V1V2 side chain is colored from green for sequence-conserved to red for sequence-variable positions. The space occupied by glycans is shown by gray dot-envelopes. The space that can reasonably be occupied by energetically favorable conformational flexibility of the crown segment of the V1 loop and the attached N137-linked glycan is shown as an orange cloud. Color images available online at www.liebertpub.com/aid