Ty virus-like particles in the Saccharomyces cerevisiae strain NCYC74.

Electron microscopic analysis of thin sections of Saccharomyces cerevisiae NCYC74 has revealed the presence of many clumped cytoplasmic particles that morphologically resemble Ty element virus-like particles (VLPs). Accumulation of Ty VLPs has only previously been observed in S. cerevisiae strains that over-express a cloned Ty element. The particles in NCYC74 co-purify with Ty RNA, Ty-specific antigens and a reverse transcriptase activity. Furthermore, they appear to be recognized by antibodies to Ty VLPs during indirect immunofluorescence experiments. These observations provide compelling evidence that the cytoplasmic particle in NCYC74 are indeed Ty VLPs.