Spelling suggestions: "subject:"buclear trafficking"" "subject:"buclear traffickings""
1 |
Identification of the membrane association of BV/ODV E26 and the domains in BV/ODV E26 responsible for nuclear trafficking to intranuclear microvesiclesBurks, Jared K. 25 April 2007 (has links)
The baculovirus Autographa californica nucleopolyhedrovirus (AcNPV) has two
viral forms, budded virus (BV) and occlusion derived virus (ODV). The envelopment of
these two viral forms occurs at different locations: BV acquires envelopes at the plasma
membrane while ODV acquires envelopes in the nucleus. The two viral forms carry out
different functions in the viral life cycle. The purpose of this study is to investigate how
viral envelope proteins sort/traffic to the nucleus. Of particular interest is BV/ODV E26
(E26). E26 is an envelope protein of both BV and ODV (Braunagel and Summers,
1994); therefore it must traffic to the plasma membrane and the nucleus during infection.
Thus, E26 is a bi-directional trafficking protein, which interacts with membranes in both
locations of the cell. As such it has been shown that there are several immunoreactive
forms of E26 (Beniya, Braunagel, and Summers, 1998). The da26 gene produces at
least 2 protein products of 26 and 28 kDa with different functions respectively, which
correlate with localization, solubility, membrane association, and temporal requirements.
The 28 kDa form is likely a soluble protein that interacts with transcriptional activators
and DNA in the nucleus in the early stages of infection. A part of the 26 kDa population
is a membrane bound form interacting with an integral membrane protein in the ER and
likely functions as an INM sorting factor. The 26 kDa membrane bond form is also
found in the inner nuclear membrane, intra-nuclear microvesicles, ODV envelopes, and
ODV in the nucleus.
|
2 |
Trafficking of integral membrane proteins of the inner nuclear membrane can be mediated by the ''sorting motif'' of autographa californica nucleopolyhedrovirus odv-e66Williamson, Shawn T 30 October 2006 (has links)
The amino-terminal 33 amino acids of the baculovirus integral membrane
protein, ODV-E66, are sufficient for localization of fusion proteins to viralinduced
intranuclear microvesicles (MV) and occlusion derived virus envelopes
during infection, and has been termed the sorting motif (SM). When abundantly
expressed, SM-fusions are also detected in the inner nuclear membrane (INM),
outer nuclear membrane and endoplasmic reticulum of infected cells, suggesting
proteins with the SM use the same trafficking pathway as cellular INM proteins
to traffic to nuclear membranes. This study identifies the essential
characteristics required for sorting of the SM to the INM of uninfected cells, and
the MV and ODV envelopes of infected cells. These features are an 18 amino
acid transmembrane sequence that lacks polar and charged amino acids (a.a.)
with a cluster of charged a.a. spaced 5-11 residues from the end of the
transmembrane sequence. A comparison of the a.a. sequence of these SM
features with cellular INM proteins shows the features are conserved.
The model of INM protein sorting and localization predicts the only known
sorting event during INM protein trafficking is immobilization/retention in the INM. This study uses confocal microscopy and fluorescence recovery after
photobleaching to compare the localization and mobility of lamin B receptor
(LBR) fusions (which contain SM-like sequences) to a viral SM fusion when
expressed in either mammalian or insect cells. The results show that
immobilization is not necessarily required for accumulation of proteins in the
INM. Furthermore, the results from infected cells show that an active sorting
event, likely independent of immobilization, can distinguish the viral SM from
cellular sequences similar to the SM.
The results of this study show that sorting of proteins to the INM can be
mediated by the viral SM or INM protein SM-like sequences that can function
either independent of, or in addition to, immobilization. These data combined
with recent reports suggest that in addition to diffusion:retention a signal
mediated mechanism for sorting and localization to the INM can occur.
|
Page generated in 0.0731 seconds