FIG. 4.
Identification of CA residues that influence the stability of HIV-1 cores. Concentrated virions were subjected to ultracentrifugation through a detergent layer into a sucrose density gradient. Yield of Cores, percentage of total CA detected in the peak fractions of cores; Relative infectivity, infectivity relative to wild-type HIV-1 as determined by a single-cycle infection assay; Cones, presence of similar quantities (compared to the wild type) of conical cores in virions (as determined by transmission electron microscopy). For R18A/N21A (+), few cones were apparent, and they were frequently aberrantly shaped; for L136D (+), cones were rarely detected. Location refers to the location of the mutation in the structure of HIV-1 CA. Shown are the mean values of at least two determinations, with error bars representing 1 standard deviation of the mean.