Abstract
Poliovirus was irradiated with u.v. light under conditions causing approx. 5% crosslinking of capsid protein to virus RNA. Cross-linked RNAprotein complexes, freed from unbound protein, were treated with nuclease, and then analysed on SDSpolyacrylamide gels. The smallest capsid polypeptide VP4 was found to be associated with the RNA to the greatest degree, followed by VP2 and VP1, while VP3 was attached only in trace amounts. Low radiation doses, which produced crosslinking of RNA to protein, did not cause breakdown of the virus particles or conformational changes of the capsid as examined physically and serologically. However, higher doses caused structural alterations of the virus capsid.