Fig. 4. K442 and K443 are essential for the activation of HPV16 through heparin.

A Visualisation of mutated site K442/443 on the L1 pentamer (pdb: 5kep)¹³. Putative binding sites are in red²⁵, and the epitope of H16.B20 antibody is in blue⁸³. B Box plot of the height of the K442/443A PsVs incubated with (N = 34) or without heparin (N = 34). P = 0.8564. C Box plot of the viral spring constant of the K442/443A PsVs incubated with or without heparin. P = 0.5524. The significance level is 0.05. The engagement of heparin did not result in significant changes in size or stiffness in K442/443A PsVs. The square in the box plots indicates the mean (also printed in Supplementary Table S1), the top and bottom of the box are the 25th and 75th percentiles, respectively, and the whiskers represent the standard deviation. The line in the box indicates the median. Source data are provided as a Source Data file.