Sequential induction of maltose-permease and maltase systems in Saccharomyces cerevisiae

The induction of maltose utilization in many strains of Saccharomyces cerevi8iae is well known. The process in resting cells involves the synthesis of maltase at the expense of the free amino acid pool Various lines of evidence (Sutton & Lampen, 1962; de la Fuente & Sols, 1962) suggest that a specific inducible permease is also necessary for maltose fermentation. Such a system, distinct from the maltotriose permease described by Harris & Thompson (1960 b), has been found in one strain by This system differs from the constitutive oc-glucoside permease, de- scribed in another strain by Robertson & Halvorson (1957), not only by virtue of its inducible character, but also because of differences in com- petitive effects between maltose and methyl oa- glucoside. The observations of Burger, Hejmovfa & Kleinzeller (1959) and Terui, Okada & Oshima (1959) also suggest that the transport of methyl oc-glucoside is not necessarily related to that of maltose. Maltose permease constitutes an 'active- transport' system (cf. The present paper describes a more detailed examination of the course of the inductive processes leading to the utilization of maltose by several strains of S. cerevisiae.