Summary: To investigate the amino acid sequence determinants for the incorporation of Vpx protein into virion particles, several mutations were introduced into the vpx gene of SIVmac239 proviral DNA, and the effects of mutations on the expression and assembly of the Vpx protein were studied. The results show that deletions of amino acids from 78 to 80 or from 82 to 87 abolished the incorporation of the expressed Vpx protein into virion particles. Other Vpx mutants, including a full-length Vpx-Vpr fusion protein and a mutant with a deletion of the C-terminal polyproline tract, were packaged efficiently. This study suggests that amino acids from 78 to 80 and 82 to 87 are important for the assembly of the Vpx protein into virus particles.
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