Isolation and characterization of a mutant of Tetrahymena thermophila blocked in secretion of lysosomal enzymes.
The development of a sensitive screening procedure for mutants of Tetrahymena thermophila blocked in secretion of lysosomal enzymes is described. By means of this procedure a mutant blocked in secretion of lysosomal enzymes has been isolated. This sec- mutant, MS-1, is constitutively blocked in release of at least six lysosomal enzymes, under both nutrient and non-nutrient conditions. MS-1 possesses, bound within the cell, the same amount of active lysosomal enzymes as the wild type. During starvation in media of low ionic strength MS-1 develops a highly vacuolated phenotype. This phenotype is caused by the sec- allele. It is reversed to a normal cell shape when the mutant is transferred to isotonic medium. The sec- mutant MS-1 contains mucocysts and is capable of inducing exocytosis of these secretory organelles, suggesting that Tetrahymena possesses at least two independent protein-secreting organelles.
Hünseler
P
P
Institute of Zoology, University of Münster, FRG.
Scheidgen-Kleyboldt
G
G
Tiedtke
A
A
D000818:Animals; D005089:Exocytosis; D006867:Hydrolases / Q000096:biosynthesis*; D008247:Lysosomes / Q000201:enzymology*; D008854:Microscopy, Electron; D009154:Mutation; D013768:Tetrahymena / Q000201:enzymology / Q000302:isolation & purification* / Q000648:ultrastructure
D006867:Hydrolases