Binding properties of avian retroviral proteins. I. Preparation and basic characterization of ASLV NC(p12) and MA(p19).

Using SP-Sephadex column chromatography we isolated from an avian retrovirus, AMV(MAV), nucleic acid-binding proteins ASLV NC(p12) and MA(p19). As shown by several criteria, namely SDS-PAGE, PR(p15) protease activity, and nucleic acid binding assay with the use of both ss and ds DNAs, our NC(p12) and MA(p19) isolates are virtually pure proteins mutually not cross-contaminated. Rabbit anti-NC(p12) and anti-MA(p19) sera which we prepared did not cross-react mutually. We conclude that both NC(p12) and MA(p19) and antibodies against them are adequately pure preparations for investigating their nucleic acid binding specificities towards AMV(MAV) genomic RNA and MAV-1 proviral DNA using electron microscopy supported by computer analysis of electron micrographs.