Selective enrichment for temperature-sensitive secretion mutants of mammalian cells using plant lectin, concanavalin A

The use of conditional mutants as a genetic approach to study protein secretion in mammalian cells requires the isolation of a large number of mutants. Because a procedure for the direct selection of mutants with secretion defects is not available, their isolation depends upon the selective enrichment of mutant phenotypes in a cell population. We have devised an enrichment strategy in which rat hepatoma cells unable to replace surface membrane receptors of a plant lectin, concanavalin A, are resistant to the cytotoxic effects of this lectin when administered at a nonpermissive temperature. This treatment yields a population highly enriched in cells that demonstrate temperature-sensitive secretion. Therefore, this selection strategy has important application in isolating temperature-sensitive mutants for use in the study of the mammalian cell secretion pathway.