A genetic selection for isolating cDNA clones that encode signal peptides.

Publisher Summary Several techniques identify cDNA clones encoding signal sequences. The yeast cell approaches use a genetic selection to identify signal sequences and consequently are more efficient and more sensitive. The selection is for secretion of invertase, a Saccharomyces cerevisiae protein that must be secreted for yeast to utilize sucrose and raffinose as carbon sources. In the application, mammalian cDNA fragments that are ligated adjacent to a truncated invertase gene provide the signals for protein synthesis and secretion. Invertase is a propitious choice for a reporter protein for this application. Invertase secretion and activity are tolerant of many different amino-terminal extensions and that secretion of as little as 2.6% of wild-type levels gives growth detectable above background. Thus, even cDNA invertase protein fusions that produce small amounts of invertase activity can be detected.