Scott W. Eastman

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The human immunodeficiency virus (HIV) type-1 viral protein U (Vpu) protein enhances the release of diverse retroviruses from human, but not monkey, cells and is thought to do so by ablating a dominant restriction to particle release. Here, we determined how Vpu expression affects the subcellular distribution of HIV-1 and murine leukemia virus (MLV) Gag(More)
HECT (homologous to the E6AP C terminus) ubiquitin ligases have diverse functions in eukaryotic cells. In screens for proteins that bind to the HECT ubiquitin ligase WWP1, we identified Spartin, which is also known as SPG20. This protein is truncated in a neurological disease, Troyer syndrome. In this study, we show that SPG20 associates with the surface of(More)
Foamy viruses (FV) are unusual retroviruses that differ in many aspects of their life cycle from the orthoretroviruses such as human immunodeficiency virus. Similar to Mason-Pfizer monkey virus (MPMV), FV assemble into capsids intracellularly. The capsids are then transported to a cellular membrane for acquisition of envelope (Env) glycoproteins and(More)
Many enveloped viruses exploit the class E vacuolar protein-sorting (VPS) pathway to bud from cells, and use peptide motifs to recruit specific class E VPS factors. Homologous to E6AP COOH terminus (HECT) ubiquitin ligases have been implicated as cofactors for PPXY motif-dependent budding, but precisely which members of this family are responsible, and how(More)
In contrast to all retroviruses but similar to the hepatitis B virus, foamy viruses (FV) require expression of the envelope protein for budding of intracellular capsids from the cell, suggesting a specific interaction between the Gag and Env proteins. Capsid assembly occurs in the cytoplasm of infected cells in a manner similar to that for the B- and D-type(More)
Endosomal sorting complex required for transport-I (ESCRT-I) is one of three defined protein complexes in the class E vacuolar protein sorting (VPS) pathway required for the sorting of ubiquitinated transmembrane proteins into internal vesicles of multivesicular bodies. In yeast, ESCRT-I is composed of three proteins, VSP23, VPS28, and VPS37, whereas in(More)
Foamy viruses (FVs) assemble using pathways distinct from those of orthoretroviruses. FV capsid assembly takes place near the host microtubule-organizing center (MTOC). Assembled capsids then migrate by an unknown mechanism to the trans-Golgi network to colocalize with the FV glycoprotein, Env. Interaction with Env is required for FV capsid egress from(More)
Foamy virus (FV) replication is distinct from that of all other retroviruses in many respects, including viral assembly. In fact, the viral assembly pathway is rather similar to that of hepadnaviruses such as hepatitis B virus. Foamy virus Gag does not contain landmark retroviral assembly domains such as the major homology region, Cys-His boxes, or a(More)
Rat fibroblasts transformed by a temperature-sensitive mutant of murine p53 undergo a reversible growth arrest in G1 at 32.5 degrees C, the temperature at which p53 adopts a wild-type conformation. The arrested cells contain inactive cyclin-dependent kinase 2 (cdk2) despite the presence of high levels of cyclin E and cdk-activating kinase activity. This is(More)
Analogous to cellular glycoproteins, viral envelope proteins contain N-terminal signal sequences responsible for targeting them to the secretory pathway. The prototype foamy virus (PFV) envelope (Env) shows a highly unusual biosynthesis. Its precursor protein has a type III membrane topology with both the N and C terminus located in the cytoplasm.(More)