Abstract
Identification of several additional restriction endonuclease sites within the cellular substitution (amv) inserted into the avian myeloblastosis virus proviral genome has permitted isolation of different regions of the amv sequence. These subsets of the avian myeloblastosis virus transforming gene were cloned in the plasmid pBR322 and used as hybridization probes to investigate the topology of homologous (proto-amv) normal chicken DNA sequences. The cellular proto-amv sequences in C/O chicken DNA are interrupted by at least 1 intervening sequence. A partial arrangement of the proto-amv sequences is presented.