Table 2.
STEM Mass and Cryo-EM Size Measurements on Released Immature and Mature HIV-1
| Immature + PFA | Mature + PFA | Mature + 2AT | Total | |
|---|---|---|---|---|
| Cryo-EM radius (nm) | 65 ± 17 (n = 150) | 65 ± 8 (n = 150) | 69 ± 16 (n = 150) | 66 ± 17 (n = 450) |
| STEM radius (nm) | 64 ± 16 (n = 84) | 60 ± 18 (n = 162) | 61 ± 17 (n = 96) | 61 ± 17 (n = 342) |
| STEM HIV-1 mass (Mda) | 319 ± 93 (n = 84) | 292 ± 89 (n = 162) | 304 ± 103 (n = 96) | 302 ± 94 (n = 342) |
| STEM TMV mass (kDa/Å) | 14.86 ± 1.63 (n = 168) | 14.06 ± 0.81 (n = 324) | 14.11 ± 0.90 (n = 192) | 14.27 ± 1.14 (n = 684) |
| Corrected STEM HIV-1 mass (Mda) | 281 ± 82 (n = 84) | 272 ± 83 (n = 162) | 282 ± 96 (n = 96) | 277 ± 86 (n = 342) |
Immature and mature HIV-1 (NL4-3) particles were purified from infected MT-4 cells and inactivated with either PFA or 2AT. Size measurements by cryo-EM were performed on the same virus preparations used for STEM. Since there was no significant change in mass or size due to the method of inactivation or proteolytic maturation, these data were pooled to yield the numbers in the last column (total). The true TMV mass per length is 13.1 kDa/Å, and the ratio of measured and true TMV mass was used for calibration to calculate the corrected HIV mass.