DETECTION OF POTATO MOP-TOP VIRUS CAPSID READTHROUGH PROTEIN IN VIRUS-PARTICLES

Potato mop-top furovirus (PMTV) RNA 3 encodes the 20 kDa coat protein and a larger readthrough protein of 67 kDa. The readthrough protein is expressed by suppression of the amber stop codon which terminates the coat protein gene. A 21 kDa C-terminal fragment of the readthrough pr otein was cloned, fused to glutathione S-transferase and expressed in E. coli. An antiserum prepared against purified fusion protein was use d in ELISA to detect the readthrough protein in extracts of PMTV-infec ted leaves. Immunogold labelling studies showed that the readthrough p rotein was located near one extremity of some of the virus particles.