In addition to their application as biotherapeutics or vaccines, recombinant proteins are increasingly being utilised as substrates for rational drug design, small-molecule drug screening, and assay development. The existence of extensive homology between basic processes in yeast and higher cells created numerous opportunities to exploit yeast as a model system for the discovery of agents that have activity on mammalian cells.
Yeasts provide a useful system for drug testing in several ways.
First, their use for growth-based assays for various screens, second as model organism for investigation of complex eukaryotic cellular processes and third, their use as a recombinant system for analysis and validation of therapeutic target proteins from higher eukaryotes. Recent progress in human genetic diseases provided a preview of the impact which the complete sequencing of the S. cerevisiae genome would have on understanding the biology of multicellular eukaryotes. When a human gene that is mutated in a disease process is identified, sequence similarity with one or more genes of known function in yeast can suggest the function performed by the human gene. Cross-species connections of this type also allow experimental approaches from model organisms to be applied to the functional analysis of the human disease gene. Electrical responses of the nervous system underlie smelling, tasting, hearing, touching and vision.