Probability of finding an <i>N</i>-linked glycosylation site at a position 1–5 amino acids from a disulphide bridge in gp120.

<p>The positions and levels of conservation of <i>N</i>-linked glycosylation sites in HIV-1 gp120 were determined using the N-glycosite software available on the HIV sequence database website [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0130621#pone.0130621.ref011" target="_blank">11</a>], based on an alignment of consensus sequences of 19 HIV-1 subtypes (2004) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0130621#pone.0130621.ref011" target="_blank">11</a>]. The probability of finding <i>N</i>-glycosylation sites closeby cysteines involved in disulphide bridges was calculated. The graph shows the relative probabilities of a glycosylated asparagine at 1, 2, 3, 4 or 5 amino acid positions away from the cysteines involved in disulphide bridges. Negative amino acid positions correspond to positions at the N-terminal site of the cysteine, positive amino acid positions correspond to positions at the C-terminal site of the cysteine. The cysteine itself is shown as a black bar. The striped line indicates the probablities in case of random distribution of <i>N</i>-glycosylation sites. (A) <i>N</i>-glycosylation sites with at least 50% conservation. (B) <i>N</i>-glycosylation sites with less than 50% conservation.