UniProt's curated description of the entry, used here for the GR-box, PTAP/PSAP L domain, NLS and chain definitions and for the spumaretrovirus-specific features of Gag processing and budding. All functional statements in the record carry ECO:0000250 (by similarity), consistent with protein existence level 3, so it is cited as curated summary rather than as experimental evidence for this isolate.

Incoming foamy virus Gag and the viral DNA genome localize at the centrosome of resting primary fibroblasts and CD4-positive T cells and persist there for weeks as unprocessed capsids; cell-cycle re-entry triggers Gag cleavage, nuclear import and productive infection.

The paper contains no chromosome or chromatin assay. The only occurrence of "chromosomes" in the full text is a general introductory statement about retroviral pre-integration complexes, and the word "chromatin" does not occur at all, so the paper cannot support the GO:0044383 host chromosome annotation keyed to it.

Wild-type PFV Gag distributes between cytoplasm, nucleus and a nucleocytoplasmic pattern in transfected HeLa cells, scored by confocal immunofluorescence over three experiments of 200 cells (Figure 1D). This is the direct localization evidence behind the host cell nucleus annotation.

A leptomycin B-sensitive, CRM1-dependent nuclear export signal at aa 95-112 of Gag is required for the late stages of replication; deletion or point mutation of it redistributes Gag into the nucleus and blocks capsid assembly and egress, and the mutant sequesters wild-type Gag in the nucleus.

The apparent cell-to-cell spreading and nuclear accumulation of PFV Gag, and of its isolated GR box II fused to GFP, occurs only after methanol fixation and never in living cells or after glutaraldehyde fixation; the authors conclude it is an artificial diffusion event during fixation, followed by nuclear retention mediated by the chromatin-binding sequence in GR box II.

The paper's own positive statement that Gag is nuclear is a citation to earlier studies rather than new data, and it notes that the GR box II nuclear localization signal has been challenged.

A short C-terminal domain of foamy virus Gag binds host chromosomes by interacting with H2A/H2B core histones; mutating it abolishes chromosomal attachment of incoming subviral complexes and prevents proviral integration while leaving particle production, entry and intracellular trafficking intact.

Foamy virus Gag targets the pericentrosomal region in transfected cells without any other viral component, in a microtubule- and dynein/dynactin-dependent manner, through a 30-residue N-terminal coiled-coil motif and a direct interaction with dynein light chain 8 (DYNLL1).

PFV Gag carries PSAP, PPPI and YEIL motifs. PSAP acts as a conventional class E VPS L domain, interacting with TSG101 in a PSAP-dependent manner in yeast two-hybrid; PPPI supports release by a Vps4-independent route; YEIL is required at an assembly step before budding.

Foamy virus release requires a highly specific Gag-Env interaction that heterologous Env cannot complement; the determinant maps to an N-terminal helical region of Gag, and the N-terminal 129 residues suffice for release while their loss abolishes it.

The expressed C-terminal GR-box region of foamy virus Gag, the functional equivalent of the orthoretroviral nucleocapsid domain, binds both RNA and DNA with high affinity and without sequence specificity in filter-binding assays; GR box I is required for binding and for replication.

A revertant lacking GR box II shows little nuclear transport of Gag yet replicates in tissue culture, which the authors read as evidence that nuclear localization of Gag is not critical for infection. This is the main contradiction behind the knowledge gap recorded on the chromatin-tethering core function.

Deletion and substitution of each GR box in a four-plasmid PFV vector system leaves particle release and genomic RNA packaging largely intact but drastically reduces particle-associated DNA content and infectivity; GR box I mutants have altered particle morphology and GR box II mutants lose the typical nuclear localization pattern of Gag.

Cryo-EM and cryo-electron tomography of purified PFV show a capsid of constant dimension plus a less ordered shell between capsid and membrane attributed to the Gag N-terminal domain together with the cytoplasmic part of the Env leader peptide gp18LP, with trimeric Env spikes in the viral membrane.

SFVcpz, the isolate this UniProt entry describes, is a distinct chimpanzee foamy virus from human foamy virus / prototype foamy virus, clustering with it at 86-95% amino-acid identity gene by gene. This is the basis for treating the CACAO rows as cross-isolate transfers requiring ISS rather than experimental codes.