A-Mating factor

Saccharomyces cerevisiae Synthetic HRP C gene fused in-frame to pre-pro a-mating factor. Constitutive and inducible promoters tried. Low Low levels of h3rperglycosylated enzyme secreted yield approx. 50 xg liter" (71, 72). 

The first evidence for the existence of the methylation of a prenylated peptidyl substrate was found in two jelly fungi, Tremella mesenterica and Tremella brasiliensis [30,31]. These peptide sequences are similar to the a-mating factor found in Saccharomyces cerevisiae, which is also prenylated at the C-terminus and contains an a-carboxyl methyl ester [32]. The gene product of the STEM in S. cerevisiae was found to be responsible for the methylation event for the a-factor-mating pheromone and the enzymatic activity of this methyltransferase was found only in the cellular membrane fractions [33,34]. Further analyses of Stel4p via epitope tagging determined that the enzyme is localized to the ER membrane and possesses six transmembrane segments, with majority of the enzyme exposed to the cytosol [35,36]. 

As discussed in Chapter 22, these pheromones control mating between haploid yeast cells of the opposite mating type, a or a. An a haploid cell secretes the a mating factor and has cell-surface receptors for the a factor an a cell secretes the a factor and has cell-surface receptors for the a factor (see Figure 22-13). Thus each type of cell recognizes the mating factor produced by the opposite type. Activation of the MAP kinase pathway by either the a or a receptors in-... 

Segall, J. E. (1993) Polarization ofyeast cells in spatial gradients of a mating factor. Proc. Natl. Acad. Sci. USA 90, 8332-8336. 

Figure 2. Structures of glycosylated a-mating factor and peptide T...

The physiological properties of the a-mating factor and its analogs could be explained by means of conformational consideraticms. H-NMR inve gaticms revealed a folded conformation of the native peptide. 

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