Figure 7.

Transport of invertase is not affected by lst1Δ. Wild-type (CKY540), lst1Δ (CKY542), and sec12-4 (CKY541) strains expressing invertase from the constitutive pTPI1–SUC2 fusion, were grown to exponential phase at 24°C in SMM medium, pH 6.5, without methionine. Wild-type and lst1Δ strains were shifted to 37°C, grown for 3 h, and the sec12-4 (CKY541) strain was shifted to 37°C 5 min before labeling. Cells were pulse-labeled with [³⁵S]methionine and cysteine for 5 min and then chased by the addition of an excess of unlabeled methionine and cysteine. Invertase was immunoprecipitated from labeled extracts and resolved by SDS-PAGE. Positions of the core glycosylated ER form and mature Golgi and secreted forms of invertase are indicated.