Thread by @Undergroundcou1

Lame 2-pp "prefusion" stabilization (i.e., inserting two consecutive prolines in hinge region of S2) is not going to disrupt the heparin sulfate binding capacity of the vaccine spike constructs owing to the fact NTD, RBD, FCS and R815 S2 are all documented sites of interaction

https://twitter.com/Undergroundcou1/status/1481243135376334856

This diagram shows the heparin sulfate binding sites in the non-NTD regions of the spike (shown in blue).

See highlighted text below indicating that heparin sulfates are able to bind to both open and closed states of the spike.

As for the NTD heparin sulfate binding site (Residues 245 to 246), here's a good citation
pubmed.ncbi.nlm.nih.gov/33968333/

As it relates to the "updated" spike vaccine constructs they're planning, let's not forget that the variant spike mutations in all regions are evolving toward more positive overall charge in certain critical areas to enhance interaction w heparin sulfate
pubmed.ncbi.nlm.nih.gov/34406867/

Shit show folks!