The purification and characterization of an intracellular sex-specific mannan protein from yeast.

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Abstract
A factor can be extracted from cells of 1 mating type (strain 5) of the yeast Hansenula wingei, which possesses the biological activity identical to a similar substance inferred to be on the surface of these cells. A kinetic analysis of the disruption process shows that the extracted material exists preformed in the cytoplasm, and is not derived by comminution of the cell wall. The factor has been purified by differential centrifugation and specific adsorption to and elution from cells of the opposite mating type. Sucrose gradient ultracentrifugation reveals that the substance exists in at least 4 particles of different sizes, and the approximate sedimentation constants of the lightest 3 are S20,w 3.5, 6.5, and 9.0. It is possible that the heavier forms are multiple'' aggregates of the lightest particle, which may be the ultimate subunit possessing biological activity. The purified factor possesses approximately equal amounts of protein and carbohydrate, and the only sugar found in hydrolysates is mannose. The biological activity of the purified factor is destroyed by proteolytic enzymes and mercaptoethanol, but not by heat or periodate. A similar factor could not be found in cells of the opposite mating type or in a diploid hybrid of the 2 mating types.