Ty3 GAG3 and POL3 genes encode the components of intracellular particles

Ty3 is a Saccharomyces cerevisiae retrotransposon that integrates near the transcription initiation sites of polymerase III-transcribed genes. It is distinct from the copialike Ty1 and Ty2 retrotransposons of S. cerevisiae in both the sequences of encoded proteins and gene order. It is a member of the gypsylike family of retrotransposons which resemble animal retroviruses. This study was undertaken to investigate the nucleocapsid particle of a transpositionally active gypsylike retrotransposon. Characterization of extracts from cells in which Ty3 expression was induced showed the presence of Ty3 nucleoprotein complexes, or viruslike particles, that migrated on linear sucrose gradients with a size of 156S. These particles are composed of Ty3 RNA, full-length, linear DNA, and proteins. In this study, antibodies raised against peptides predicted from the Ty3 sequence were used to identify Ty3-encoded proteins. These include the capsid (26 kDa), nucleocapsid (9 kDa), and reverse transcr...