Constitutive and Induced Excretion of Polypeptides in Tetrahymena thermophila1

Polypeptides normally excreted to growth or starvation media were revealed using O'Farrell gel-electrophoresis and silver-staining. The major polypeptides detected in conditioned media were either constitutive, growth specific, starvation specific, or high-Tris specific. The majority of the excreted polypeptides could be released from the cells by a hypo-osomotic shock, possibly resulting in membrane leakage, but also mucocyst and/or plasma membrane-associated polypeptides were detected in the conditioned media.