Biology Reference
In-Depth Information
Fig. 7
Egress of nucleocapsid. Shown here is a drawing illustrating some features of the herpes-
virus egress pathway.
1
Intranuclear capsids bud through the inner nuclear membrane by a primary
envelopment process requiring the homologs of CMV pUL50 and pUL53 (represented by
clus-
tered short lines
on inner and outer nuclear membranes).
2
Resulting enveloped particle in peri-
nuclear space represents a translocation intermediate.
3
De-envelopment at the outer nuclear
membrane releases the nucleocapsid into the cytoplasm where it acquires final complement of
tegument proteins (
small lines and circles
; also depicted in nucleus and perinuclear space to indi-
cate uncertainty about site(s) of addition).
4
Fully tegumented capsid buds into cytoplasmic vesi-
cles or tubules, through which it completes egress from the cell. The presence of tegumented
B-capsids undergoing secondary envelopment in the cytoplasm (see Fig. 1d), indicates this
mechanism is not selective for DNA-containing particles
nuclear lamina proteins underlying the inner nuclear membrane, weakening their
interaction and dissolving the barrier they pose to capsid egress (Muranyi et al.
2002). Interaction of the membrane-associated member of the nuclear-egress pair
(e.g., CMV pUL50) with its nuclear phosphoprotein partner (e.g., CMV pUL53)
may then drive primary envelopment (Mettenleiter 2002; Muranyi et al. 2002;
Bjerke et al. 2003).
