Biology Reference
In-Depth Information
Fig. 7.
Moloney murine leukemia virus (M-MuLV). (
a, b
) Wild-type
env
+
virion exhibiting dense arrangements of protein “tufts” on its surface:
(
a
) whole viron and (
b
) high-resolution. (
c
) A virion of the M-MuLV env
−
mutant lacking the gene for the envelope glycoprotein shows indeed a “bald”
surface lacking the surface proteins. The irregular surface character is a con-
sequence of the deformable and unstable membrane surface. (
d
) Isolated
MuLV virions show the appearance of protruding blebs (arrows), never more
than one per virion, that are likely to be scars resulting from the budding
process. (
e
) MuLV virions emerging from an infected NIH 3T3 fibroblast
cell. The granular background is the 3T3 cell surface. (
f
) The surface of an
NIH 3T3 cell infected with the MuLV mutant gPr80
gag
. The emerging
mutant virions are unable to mature and separate from the cell surface, and
instead form prominent tube-like protrusions on the cell surface. The cells in
(
e, f
) were fixed with gluteraldehyde and dehydrated with, and imaged under,
ethanol to enable AFM imaging.
upon the force exhibited by the AFM probe during scanning. It was
suggested that the surfaces of the env
−
virions contain a lower den-
sity of associated proteins, which have markedly unstable mechanical
properties.
