FIG. 1.

Schematic representation of PPXY mutations in the MGF minigenome. MGF stands for the M, G, and GFP minigenome. l and t denote the leader and trailer sequences, respectively. The hepatitis delta virus ribozyme sequence (HDV) and the T7 terminator sequence (ΦT) are represented by hatched boxes. Arrows indicate the direction of transcription for each gene. The solid box at the 5′ end of the M gene represents the N-terminal region of the matrix protein including the PPXY motif, which is enlarged below. The numbering shows the positions of amino acids with respect to the N terminus of M protein. Alanine substitutions were made for the proline and tyrosine residues either singly or in combinations. The name of each mutant is listed on the right. WT stands for the wild-type sequence of the PY motif in VSV M protein. The mutants were classified into two groups, P and Y mutants, based on the severity of their phenotypes.