SV40 Mutant tsA1499 Is Heat-sensitive for Lytic Growth but Generates Cold-sensitive Rat-cell Transformants

Abstract

The SV40 A gene codes for large T antigen (Rundell et al. 1977). The A gene occupies almost one half of the SV40 genome; the 5′ end of its mRNA is at 66 map units and its 3′ end is at 15 map units (Fig. 2) (Berk and Sharp 1978). A large number of temperature-sensitive (ts) mutants have been isolated that belong to the A complementation group and are phenotypically temperature-sensitive for lytic growth and transformation (Tegtmeyer and Ozer 1971; Tegtmeyer 1972; Chou and Martin 1974). Lai and Nathans (1975) mapped 11 of these mutants by a marker-rescue procedure and found their mutations to be clustered in a small segment of the A gene. Ten mutations map between 32 and 42.5 map units (rescued by the HinII + III H and I fragments), and one mutation, tsA7, is located between 17 and 32 map units (rescued by the HinII +...