A Trans-acting Protein Kinase Identified in Cells Transformed by Abelson Murine Leukemia Virus

Abelson murine leukemia virus (Ab-MuLV) is a transformation-defective retrovirus derived from the Moloney murine leukemia virus (M-MuLV). The basic biology, genomic structure, mRNA species, protein translation products, and serological characterization of Ab-MuLV are reviewed elsewhere (Baltimore et al., this volume). The prototype Ab-MuLV strain is known to encode a single major polyprotein with a molecular weight (m.w.) of 120,000 (P120) and an amino-terminal region (--30,OOOm.w.) derived from retained sequences of the M-MuLV genome. A car-boxyterminal region (-90,000 m.w.) encoded from the Ab-MuLV unique sequences contains distinctive anti-genic determinants 0Nitte et al. 1978, 1979). Recently, strain variants have been isolated tha